Not counting the Steam Deck, since KDE isn’t actually turned on while you’re running games.
Normally I’m a Gnome guy, but I’m building a tiny low power portable computer and wanting to keep resource utilization low, so I’m investigating other options.
Mostly just fine with i3 my experience. Sometimes I have to move the game window to a different workspace if I want to interact directly with steam, or whatever else I have in the same workspace that I launched the game in, because it keeps forcing it self exclusive/full screen. In some instances, depending on the game, that might mess things up (crash, freeze, missing/stuck mouse cursor), but most of the time it works just fine.