Did you install EasyEffects and other apps with flatpak? If so you need to add some override flag, can’t remember what it is but it should be easy to find, maybe arch wiki etc.

Have you searched gnome-looks.org?

Not really afaik, you can make file immutable with chattr +i /path/to/something but that means you cannot write to it either, which will probably cause problems.

Revolt is very promising, not ready yet but already feels very similar to Discord

git gud?