It really depends on the type of game you play. As everyone points out, kernel level anti-cheat is a problem on Linux, but also games that require odd controllers have trouble as well. One game I play, Farming Simulator 22, doesn't work well on Linux because they use the raw windows input from joysticks and wheels. You can still play with mouse and keyboard, but the fun isn't there.

I was pleasantly surprised at just how many of my games worked well on my new Ubuntu install. Even more so at how many games are playable on my Xubuntu Chromebook install.

I have occasional issues mainly with graphics drivers or anti-cheat. Otherwise thought it's remarkably stable. I've also gotten a lot of non-Steam games to work fine.

Same. I admittedly don't play a lot of new games, and I don't do online games, but like 95% things Just Work when I load a Steam game on my box. The remaining five percent are fixed if I change the Proton version to GE Proton.

I played through Miles Morales at full specs a few weeks ago, and it ran just about perfectly as far as I could tell.

On the games that won't work well, last time I looked at it anything VR was a huge PITA (e.g. https://github.com/chaosmaou/wivrn-guide)

That's where Valve's Frame brought huge expectations.