It’s truly a non-issue, unless we’re talking competitive multiplayer games. The only single player game I can think of that I’ve had Linux-related problems with since I switched my desktop over a couple years ago has been the new Indiana Jones game, and that was patched within a week of launch. Proton makes it brain-dead easy. I have a pretty big library and not many games have official support, but they just work with Proton. I don’t do any tinkering with custom proton builds or anything either. On a fresh Steam install, you have to go into settings once to enable Proton in games that haven’t been tested with it, but then you just forget about it and play like you would on Windows.