diff --git a/packages/docusaurus-mdx-loader/src/remark/admonitions/index.ts b/packages/docusaurus-mdx-loader/src/remark/admonitions/index.ts
index d45e2e9219ca..fd34e3579ffb 100644
--- a/packages/docusaurus-mdx-loader/src/remark/admonitions/index.ts
+++ b/packages/docusaurus-mdx-loader/src/remark/admonitions/index.ts
@@ -5,17 +5,11 @@
  * LICENSE file in the root directory of this source tree.
  */
 // @ts-expect-error: TODO see https://github.com/microsoft/TypeScript/issues/49721
-import type {Transformer, Processor} from 'unified';
+import type {Transformer, Plugin} from 'unified';
 
 // @ts-expect-error: TODO see https://github.com/microsoft/TypeScript/issues/49721
 import type {ContainerDirective} from 'mdast-util-directive';
-import type {Parent} from 'mdast';
-
-// TODO as of April 2023, no way to import/re-export this ESM type easily :/
-// This might change soon, likely after TS 5.2
-// See https://github.com/microsoft/TypeScript/issues/49721#issuecomment-1517839391
-// import type {Plugin} from 'unified';
-type Plugin = any; // TODO fix this asap
+import type {Parent, Root} from 'mdast';
 
 export type AdmonitionOptions = {
   keywords: string[];
@@ -85,10 +79,10 @@ function getTextOnlyTitle(directiveLabel: DirectiveLabel): string | undefined {
     : undefined;
 }
 
-const plugin: Plugin = function plugin(
-  this: Processor,
-  optionsInput: Partial<AdmonitionOptions> = {},
-): Transformer {
+const plugin: Plugin<Partial<AdmonitionOptions>[], Root> = function plugin(
+  this,
+  optionsInput = {},
+): Transformer<Root> {
   const {keywords} = normalizeAdmonitionOptions(optionsInput);
 
   return async (root) => {
@@ -96,31 +90,30 @@ const plugin: Plugin = function plugin(
 
     visit(root, (node) => {
       if (node.type === 'containerDirective') {
-        const directive = node as ContainerDirective;
-        const isAdmonition = keywords.includes(directive.name);
+        const isAdmonition = keywords.includes(node.name);
 
         if (!isAdmonition) {
           return;
         }
 
-        const {directiveLabel, contentNodes} = parseDirective(directive);
+        const {directiveLabel, contentNodes} = parseDirective(node);
 
         const textOnlyTitle =
-          directive.attributes?.title ??
+          node.attributes?.title ??
           (directiveLabel ? getTextOnlyTitle(directiveLabel) : undefined);
 
         // Transform the mdast directive node to a hast admonition node
         // See https://github.com/syntax-tree/mdast-util-to-hast#fields-on-nodes
         // TODO in MDX v2 we should transform the whole directive to
         // mdxJsxFlowElement instead of using hast
-        directive.data = {
+        node.data = {
           hName: 'admonition',
           hProperties: {
             ...(textOnlyTitle && {title: textOnlyTitle}),
-            type: directive.name,
+            type: node.name,
           },
         };
-        directive.children = contentNodes;
+        node.children = contentNodes;
 
         // TODO legacy MDX v1 <mdxAdmonitionTitle> workaround
         // v1: not possible to inject complex JSX elements as props
@@ -135,7 +128,7 @@ const plugin: Plugin = function plugin(
             children: directiveLabel.children,
           };
           // @ts-expect-error: invented node type
-          directive.children.unshift(complexTitleNode);
+          node.children.unshift(complexTitleNode);
         }
       }
     });
diff --git a/packages/docusaurus-mdx-loader/src/remark/contentTitle/index.ts b/packages/docusaurus-mdx-loader/src/remark/contentTitle/index.ts
index 12aa5cdc7ba9..541d5aa470cf 100644
--- a/packages/docusaurus-mdx-loader/src/remark/contentTitle/index.ts
+++ b/packages/docusaurus-mdx-loader/src/remark/contentTitle/index.ts
@@ -4,20 +4,13 @@
  * This source code is licensed under the MIT license found in the
  * LICENSE file in the root directory of this source tree.
  */
-
 // @ts-expect-error: TODO see https://github.com/microsoft/TypeScript/issues/49721
-import type {Transformer} from 'unified';
-import type {Heading, Parent} from 'mdast';
+import type {Transformer, Plugin} from 'unified';
+import type {Heading, Parent, Root} from 'mdast';
 
 // @ts-expect-error: ES support...
 import type {MdxJsxFlowElement} from 'mdast-util-mdx';
 
-// TODO as of April 2023, no way to import/re-export this ESM type easily :/
-// TODO upgrade to TS 5.3
-// See https://github.com/microsoft/TypeScript/issues/49721#issuecomment-1517839391
-// import type {Plugin} from 'unified';
-type Plugin = any; // TODO fix this asap
-
 interface PluginOptions {
   removeContentTitle?: boolean;
 }
@@ -41,9 +34,9 @@ function wrapHeadingInJsxHeader(
  * This is exposed as "data.contentTitle" to the processed vfile
  * Also gives the ability to strip that content title (used for the blog plugin)
  */
-const plugin: Plugin = function plugin(
-  options: PluginOptions = {},
-): Transformer {
+const plugin: Plugin<PluginOptions[], Root> = function plugin(
+  options = {},
+): Transformer<Root> {
   // content title is
   const removeContentTitle = options.removeContentTitle ?? false;
 
@@ -51,25 +44,26 @@ const plugin: Plugin = function plugin(
     const {toString} = await import('mdast-util-to-string');
     const {visit, EXIT} = await import('unist-util-visit');
     visit(root, ['heading', 'thematicBreak'], (node, index, parent) => {
+      if (!parent || index === undefined) {
+        return undefined;
+      }
       if (node.type === 'heading') {
-        const headingNode = node as Heading;
         // console.log('headingNode:', headingNode);
 
-        if (headingNode.depth === 1) {
-          vfile.data.contentTitle = toString(headingNode);
+        if (node.depth === 1) {
+          vfile.data.contentTitle = toString(node);
           if (removeContentTitle) {
-            // @ts-expect-error: TODO how to fix?
-            parent!.children.splice(index, 1);
+            parent.children.splice(index, 1);
           } else {
             // TODO in the future it might be better to export contentTitle as
             // as JSX node to keep this logic a theme concern?
             // See https://github.com/facebook/docusaurus/pull/10335#issuecomment-2250187371
-            wrapHeadingInJsxHeader(headingNode, parent, index!);
+            wrapHeadingInJsxHeader(node, parent, index);
           }
           return EXIT; // We only handle the very first heading
         }
         // We only handle contentTitle if it's the very first heading found
-        if (headingNode.depth >= 1) {
+        if (node.depth >= 1) {
           return EXIT;
         }
       }
diff --git a/packages/docusaurus-mdx-loader/src/remark/details/index.ts b/packages/docusaurus-mdx-loader/src/remark/details/index.ts
index ef8e0146b43c..9d387a234697 100644
--- a/packages/docusaurus-mdx-loader/src/remark/details/index.ts
+++ b/packages/docusaurus-mdx-loader/src/remark/details/index.ts
@@ -8,15 +8,14 @@
 // @ts-expect-error: TODO see https://github.com/microsoft/TypeScript/issues/49721
 import type {Transformer} from 'unified';
 
-// @ts-expect-error: ES support...
-import type {MdxJsxFlowElement} from 'mdast-util-mdx';
+import type {Root} from 'mdast';
 
 // Transform <details> to <Details>
 // MDX 2 doesn't allow to substitute html elements with the provider anymore
-export default function plugin(): Transformer {
+export default function plugin(): Transformer<Root> {
   return async (root) => {
     const {visit} = await import('unist-util-visit');
-    visit(root, 'mdxJsxFlowElement', (node: MdxJsxFlowElement) => {
+    visit(root, 'mdxJsxFlowElement', (node) => {
       if (node.name === 'details') {
         node.name = 'Details';
       }
diff --git a/packages/docusaurus-mdx-loader/src/remark/head/index.ts b/packages/docusaurus-mdx-loader/src/remark/head/index.ts
index 0bab7a76692d..ec75484c61dd 100644
--- a/packages/docusaurus-mdx-loader/src/remark/head/index.ts
+++ b/packages/docusaurus-mdx-loader/src/remark/head/index.ts
@@ -8,15 +8,14 @@
 // @ts-expect-error: TODO see https://github.com/microsoft/TypeScript/issues/49721
 import type {Transformer} from 'unified';
 
-// @ts-expect-error: TODO see https://github.com/microsoft/TypeScript/issues/49721
-import type {MdxJsxFlowElement} from 'mdast-util-mdx';
+import type {Root} from 'mdast';
 
 // Transform <head> to <Head>
 // MDX 2 doesn't allow to substitute html elements with the provider anymore
-export default function plugin(): Transformer {
+export default function plugin(): Transformer<Root> {
   return async (root) => {
     const {visit} = await import('unist-util-visit');
-    visit(root, 'mdxJsxFlowElement', (node: MdxJsxFlowElement) => {
+    visit(root, 'mdxJsxFlowElement', (node) => {
       if (node.name === 'head') {
         node.name = 'Head';
       }
diff --git a/packages/docusaurus-mdx-loader/src/remark/headings/index.ts b/packages/docusaurus-mdx-loader/src/remark/headings/index.ts
index 5f2250a9c17e..049b91059f38 100644
--- a/packages/docusaurus-mdx-loader/src/remark/headings/index.ts
+++ b/packages/docusaurus-mdx-loader/src/remark/headings/index.ts
@@ -9,22 +9,22 @@
 
 import {parseMarkdownHeadingId, createSlugger} from '@docusaurus/utils';
 // @ts-expect-error: TODO see https://github.com/microsoft/TypeScript/issues/49721
-import type {Transformer} from 'unified';
-import type {Heading, Text} from 'mdast';
+import type {Plugin, Transformer} from 'unified';
+import type {Root, Text} from 'mdast';
 
 export interface PluginOptions {
   anchorsMaintainCase: boolean;
 }
 
-export default function plugin({
+const plugin: Plugin<PluginOptions[], Root> = function plugin({
   anchorsMaintainCase,
-}: PluginOptions): Transformer {
+}): Transformer<Root> {
   return async (root) => {
     const {toString} = await import('mdast-util-to-string');
     const {visit} = await import('unist-util-visit');
 
     const slugs = createSlugger();
-    visit(root, 'heading', (headingNode: Heading) => {
+    visit(root, 'heading', (headingNode) => {
       const data = headingNode.data ?? (headingNode.data = {});
       const properties = (data.hProperties || (data.hProperties = {})) as {
         id: string;
@@ -77,4 +77,6 @@ export default function plugin({
       properties.id = id;
     });
   };
-}
+};
+
+export default plugin;
diff --git a/packages/docusaurus-mdx-loader/src/remark/mdx1Compat/codeCompatPlugin.ts b/packages/docusaurus-mdx-loader/src/remark/mdx1Compat/codeCompatPlugin.ts
index 54f67a7dfdc7..b48331aad6c0 100644
--- a/packages/docusaurus-mdx-loader/src/remark/mdx1Compat/codeCompatPlugin.ts
+++ b/packages/docusaurus-mdx-loader/src/remark/mdx1Compat/codeCompatPlugin.ts
@@ -6,8 +6,8 @@
  */
 
 // @ts-expect-error: TODO see https://github.com/microsoft/TypeScript/issues/49721
-import type {Transformer, Processor} from 'unified';
-import type {Code} from 'mdast';
+import type {Transformer, Plugin} from 'unified';
+import type {Root} from 'mdast';
 
 // Solution inspired by https://github.com/pomber/docusaurus-mdx-2/blob/main/packages/mdx-loader/src/remark/codeCompat/index.ts
 // TODO after MDX 2 we probably don't need this - remove soon?
@@ -16,11 +16,11 @@ import type {Code} from 'mdast';
 
 // To make theme-classic/src/theme/MDXComponents/Pre work
 // we need to fill two properties that mdx v2 doesn't provide anymore
-export default function codeCompatPlugin(this: Processor): Transformer {
+const plugin: Plugin<unknown[], Root> = function plugin(): Transformer<Root> {
   return async (root) => {
     const {visit} = await import('unist-util-visit');
 
-    visit(root, 'code', (node: Code) => {
+    visit(root, 'code', (node) => {
       node.data = node.data || {};
 
       node.data.hProperties = node.data.hProperties || {};
@@ -31,4 +31,6 @@ export default function codeCompatPlugin(this: Processor): Transformer {
       node.data.hProperties.live = node.meta?.split(' ').includes('live');
     });
   };
-}
+};
+
+export default plugin;
diff --git a/packages/docusaurus-mdx-loader/src/remark/mermaid/index.ts b/packages/docusaurus-mdx-loader/src/remark/mermaid/index.ts
index 92f99e2a04ab..b362b69cc5ba 100644
--- a/packages/docusaurus-mdx-loader/src/remark/mermaid/index.ts
+++ b/packages/docusaurus-mdx-loader/src/remark/mermaid/index.ts
@@ -9,17 +9,17 @@ import {transformNode} from '../utils';
 
 // @ts-expect-error: TODO see https://github.com/microsoft/TypeScript/issues/49721
 import type {Transformer} from 'unified';
-import type {Code} from 'mdast';
+import type {Root} from 'mdast';
 
 // TODO: this plugin shouldn't be in the core MDX loader
 // After we allow plugins to provide Remark/Rehype plugins (see
 // https://github.com/facebook/docusaurus/issues/6370), this should be provided
 // by theme-mermaid itself
-export default function plugin(): Transformer {
+export default function plugin(): Transformer<Root> {
   return async (root) => {
     const {visit} = await import('unist-util-visit');
 
-    visit(root, 'code', (node: Code) => {
+    visit(root, 'code', (node) => {
       if (node.lang === 'mermaid') {
         // TODO migrate to mdxJsxFlowElement? cf admonitions
         transformNode(node, {
diff --git a/packages/docusaurus-mdx-loader/src/remark/resolveMarkdownLinks/index.ts b/packages/docusaurus-mdx-loader/src/remark/resolveMarkdownLinks/index.ts
index 0eeecb06a4d2..330b2cdec6f1 100644
--- a/packages/docusaurus-mdx-loader/src/remark/resolveMarkdownLinks/index.ts
+++ b/packages/docusaurus-mdx-loader/src/remark/resolveMarkdownLinks/index.ts
@@ -12,8 +12,8 @@ import {
 } from '@docusaurus/utils';
 
 // @ts-expect-error: TODO see https://github.com/microsoft/TypeScript/issues/49721
-import type {Transformer} from 'unified';
-import type {Definition, Link} from 'mdast';
+import type {Plugin, Transformer} from 'unified';
+import type {Definition, Link, Root} from 'mdast';
 
 type ResolveMarkdownLinkParams = {
   /**
@@ -35,12 +35,6 @@ export interface PluginOptions {
   resolveMarkdownLink: ResolveMarkdownLink;
 }
 
-// TODO as of April 2023, no way to import/re-export this ESM type easily :/
-// TODO upgrade to TS 5.3
-// See https://github.com/microsoft/TypeScript/issues/49721#issuecomment-1517839391
-// import type {Plugin} from 'unified';
-type Plugin = any; // TODO fix this asap
-
 const HAS_MARKDOWN_EXTENSION = /\.mdx?$/i;
 
 function parseMarkdownLinkURLPath(link: string): URLPath | null {
@@ -64,7 +58,9 @@ function parseMarkdownLinkURLPath(link: string): URLPath | null {
  * This is exposed as "data.contentTitle" to the processed vfile
  * Also gives the ability to strip that content title (used for the blog plugin)
  */
-const plugin: Plugin = function plugin(options: PluginOptions): Transformer {
+const plugin: Plugin<PluginOptions[], Root> = function plugin(
+  options,
+): Transformer<Root> {
   const {resolveMarkdownLink} = options;
   return async (root, file) => {
     const {visit} = await import('unist-util-visit');
diff --git a/packages/docusaurus-mdx-loader/src/remark/toc/index.ts b/packages/docusaurus-mdx-loader/src/remark/toc/index.ts
index e457e61bfb06..7259ec36a228 100644
--- a/packages/docusaurus-mdx-loader/src/remark/toc/index.ts
+++ b/packages/docusaurus-mdx-loader/src/remark/toc/index.ts
@@ -15,7 +15,7 @@ import {
 } from './utils';
 import type {Heading, Root} from 'mdast';
 // @ts-expect-error: TODO see https://github.com/microsoft/TypeScript/issues/49721
-import type {Transformer} from 'unified';
+import type {Plugin, Transformer} from 'unified';
 import type {
   MdxjsEsm,
   MdxJsxFlowElement,
@@ -155,7 +155,9 @@ async function collectTOCItems({
   }
 }
 
-export default function plugin(options: PluginOptions = {}): Transformer<Root> {
+const plugin: Plugin<PluginOptions[], Root> = function plugin(
+  options = {},
+): Transformer<Root> {
   const tocExportName = options.name || 'toc';
 
   return async (root) => {
@@ -184,4 +186,6 @@ export default function plugin(options: PluginOptions = {}): Transformer<Root> {
       }),
     );
   };
-}
+};
+
+export default plugin;
diff --git a/packages/docusaurus-mdx-loader/src/remark/transformImage/index.ts b/packages/docusaurus-mdx-loader/src/remark/transformImage/index.ts
index 6799da505466..5ae25e5e3087 100644
--- a/packages/docusaurus-mdx-loader/src/remark/transformImage/index.ts
+++ b/packages/docusaurus-mdx-loader/src/remark/transformImage/index.ts
@@ -21,10 +21,10 @@ import sizeOf from 'image-size';
 import logger from '@docusaurus/logger';
 import {assetRequireAttributeValue, transformNode} from '../utils';
 // @ts-expect-error: TODO see https://github.com/microsoft/TypeScript/issues/49721
-import type {Transformer} from 'unified';
+import type {Plugin, Transformer} from 'unified';
 // @ts-expect-error: TODO see https://github.com/microsoft/TypeScript/issues/49721
 import type {MdxJsxTextElement} from 'mdast-util-mdx';
-import type {Image} from 'mdast';
+import type {Image, Root} from 'mdast';
 import type {Parent} from 'unist';
 
 type PluginOptions = {
@@ -186,7 +186,9 @@ async function processImageNode(target: Target, context: Context) {
   await toImageRequireNode(target, imagePath, context);
 }
 
-export default function plugin(options: PluginOptions): Transformer {
+const plugin: Plugin<PluginOptions[], Root> = function plugin(
+  options,
+): Transformer<Root> {
   return async (root, vfile) => {
     const {visit} = await import('unist-util-visit');
 
@@ -201,9 +203,14 @@ export default function plugin(options: PluginOptions): Transformer {
     };
 
     const promises: Promise<void>[] = [];
-    visit(root, 'image', (node: Image, index, parent) => {
+    visit(root, 'image', (node, index, parent) => {
+      if (!parent || index === undefined) {
+        return;
+      }
       promises.push(processImageNode([node, index, parent!], context));
     });
     await Promise.all(promises);
   };
-}
+};
+
+export default plugin;
diff --git a/packages/docusaurus-mdx-loader/src/remark/transformLinks/index.ts b/packages/docusaurus-mdx-loader/src/remark/transformLinks/index.ts
index 056c460956dd..46032dcb624b 100644
--- a/packages/docusaurus-mdx-loader/src/remark/transformLinks/index.ts
+++ b/packages/docusaurus-mdx-loader/src/remark/transformLinks/index.ts
@@ -18,11 +18,11 @@ import {
 import escapeHtml from 'escape-html';
 import {assetRequireAttributeValue, transformNode} from '../utils';
 // @ts-expect-error: TODO see https://github.com/microsoft/TypeScript/issues/49721
-import type {Transformer} from 'unified';
+import type {Plugin, Transformer} from 'unified';
 // @ts-expect-error: TODO see https://github.com/microsoft/TypeScript/issues/49721
 import type {MdxJsxTextElement} from 'mdast-util-mdx';
 import type {Parent} from 'unist';
-import type {Link, Literal} from 'mdast';
+import type {Link, Literal, Root} from 'mdast';
 
 type PluginOptions = {
   staticDirs: string[];
@@ -199,7 +199,9 @@ async function processLinkNode(target: Target, context: Context) {
   }
 }
 
-export default function plugin(options: PluginOptions): Transformer {
+const plugin: Plugin<PluginOptions[], Root> = function plugin(
+  options,
+): Transformer<Root> {
   return async (root, vfile) => {
     const {visit} = await import('unist-util-visit');
 
@@ -214,9 +216,14 @@ export default function plugin(options: PluginOptions): Transformer {
     };
 
     const promises: Promise<void>[] = [];
-    visit(root, 'link', (node: Link, index, parent) => {
-      promises.push(processLinkNode([node, index, parent!], context));
+    visit(root, 'link', (node, index, parent) => {
+      if (!parent || index === undefined) {
+        return;
+      }
+      promises.push(processLinkNode([node, index, parent], context));
     });
     await Promise.all(promises);
   };
-}
+};
+
+export default plugin;
diff --git a/packages/docusaurus-mdx-loader/src/remark/unusedDirectives/index.ts b/packages/docusaurus-mdx-loader/src/remark/unusedDirectives/index.ts
index b4641e522b71..2ed4fca6fe50 100644
--- a/packages/docusaurus-mdx-loader/src/remark/unusedDirectives/index.ts
+++ b/packages/docusaurus-mdx-loader/src/remark/unusedDirectives/index.ts
@@ -9,21 +9,16 @@ import process from 'process';
 import logger from '@docusaurus/logger';
 import {posixPath} from '@docusaurus/utils';
 import {transformNode} from '../utils';
+import type {Root} from 'mdast';
 
 // @ts-expect-error: TODO see https://github.com/microsoft/TypeScript/issues/49721
-import type {Transformer, Processor, Parent} from 'unified';
+import type {Transformer, Processor, Parent, Plugin} from 'unified';
 import type {
   Directives,
   TextDirective,
   // @ts-expect-error: TODO see https://github.com/microsoft/TypeScript/issues/49721
 } from 'mdast-util-directive';
 
-// TODO as of April 2023, no way to import/re-export this ESM type easily :/
-// This might change soon, likely after TS 5.2
-// See https://github.com/microsoft/TypeScript/issues/49721#issuecomment-1517839391
-// import type {Plugin} from 'unified';
-type Plugin = any; // TODO fix this asap
-
 type DirectiveType = Directives['type'];
 
 const directiveTypes: DirectiveType[] = [
@@ -130,7 +125,9 @@ function isUnusedDirective(directive: Directives) {
   return !directive.data;
 }
 
-const plugin: Plugin = function plugin(this: Processor): Transformer {
+const plugin: Plugin<unknown[], Root> = function plugin(
+  this: Processor,
+): Transformer<Root> {
   return async (tree, file) => {
     const {visit} = await import('unist-util-visit');