Basically the only games that don't work are riot games, tarkov and apex. Call of duty is hit or miss depending on the title.

Honestly if you play shooters your going to run into more issues then any other genre. For what ever reason shooter developers have a boner for hating on Linux.

Everyone else just doesn't care, and the lack of support is more out of laziness then malice.

Not quite, steam now installs EasyAntiCheat for linux when you first setup steam for instance. The games you will struggle with are games such as those published by Riot, some view that as a bonus though 😅

For the most part, no. Check out areweanticheatyet

Counter-strike works, as do all valve titles. Overwatch, Splitgate and Titanfall work as well and so do most "non-real-time games", like Trackmania. Riot's games and Rainbow don't work. Check protondb for the games that ate important to you.

Depends on the game/publisher. Depending on the anticheat it can be as simple as enabling Linux/Proton support on the dev's side with a flag.

I can't play Destiny 2 with my Destiny obsessed friend, that's about all I've been impacted. Didn't really get into it anyway. I don't even check ProtonDB anymore before buying new games, they almost all work flawlessly these days.