Userscript to Return the Dislike count on Invidious.
Support for the most popular instances is already included, if yours isnt included just add it in '==UserScript==' with the grant option, like the other domains.
// @match https://yourdomain.com/watch?v=*
Firstly you need a Userscript manager, for this i recommend Violentmonkey.
After one is installed you can go to one of the sites below and click install.