You are messed up you'r system with wrong config files or something. Try with fresh linux install and you will see that, anithing will work again. Or reset steam in command line, but you will lose all you'r games and anything in steam client. Will need redownload again.
Hello @Bitwolfies, this reads like either the selected Proton version in the global Steam Play settings, or the per-game override is set to an invalid or removed Proton version.
Nothing extracted yet.
Despite having proton enabled for all games, some games like Doom 3 BFG , or Persona 5 Strikers still claim they can only be installed on Windows systems.
Restarted the client, didn't change anythings, not sure how many games this effects, was a blacklist added?
Edit: Burnout paradise no longer appears either, another game known to be broken on proton, doesn't seem to match games that are unverified on steam deck, as I can no longer install Lego Builders journey, a deck verified game.
Edit 2: The Quake remaster as well?