It's mostly any game that has anti-cheat in it though isn't it. It's all well and good to say that only 21 games don't work, but if they are the top most played games then it's a bit of a problem.
I know it's not Linux as fault that the games don't work, but it's daft to suggest that you can just brush it aside as not a concern. I have a steam deck so if a game is Linux supported I'll just play it on that but until kennel level anti cheat is sorted (preferably by just getting rid of it) at least personally I'll have to stick to windows on my desktop.