Sometimes audio crackles, usually right before the game locks up the entire system which happenes sometimes

Sometimes the lighting can be glitched on certain parts of certain maps, happens pretty rarely

Mouse input is often less responsive than it should be, can be sometimes inaccurate, beyond 125Hz mouse polling rate its unplayable due to missed inputs. Sometimes mouse key bound weapons including on the scroll wheel click do not register, if middle click scrolling is enabled in KDE you can't look around for the duration of the middle mouse button being held down. DirectX Input sometimes seems slightly more responsive than Raw Input. The cursor will disappear in menus after a match regardless of settings, alt-tabing restores it.

Runs well often except when it doesn't, its pretty unpredictable, there are random frame drops and stutters sometimes, even when there arent it often feels less responsive than Windows, other times it runs perfectly. Often like 20-30 FPS slower than Windows. 3440x1440 Everything Ultra except High textures 90% res scale, lowering settings does not improve performance, in fact it can often lower it a lot. Alt-tabbing can sometimes lower performance in-match. Performance sometimes seems to tank after like 30+ mins of play, restarting the game usually fixes it.

Sometimes ping is higher than on Windows, issues could be due to performance or networking issues with Proton, either way same end result the game is always online so impossible to know for sure.