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.
I switched to just using a window manager two years ago, and I haven’t looked back since. Currently using qtile (WM written and configured in python) and it was pretty straight forward to install/configure. This is the video that made me want to try it out.