Disabling WebRTC on Microsoft Edge does not work

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OS: Ubuntu 22.04.4 LTS x86_64
Kernel: 6.5.0-21-generic
DE: GNOME 42.9
Microsoft Edge is installed with Flatpak, Version 126.0.2592.87 (Official build) (64-bit)
Tried your method:

Open Edge and type: about:flags in the Address Bar & press Enter
You’ll see WebRTC here. Under that, there’s an Option to hide your real IP Address. Check the Box: Hide my local IP address over WebRTC connections to activate.

But now if I open the https://proxy6.net/en/privacy in both general and "InPrivate" window, it still shows the WebRTC is open. The settings work well on Firefox, the WebRTC is completely down. I really have no idea what is going on with Edge.