It might be because one of my monitors is actually a graphics tablet. GNOME’s scaling just didn’t work in either session such that all three monitors were scaled correctly, but KDE’s Wayland session was able to handle it properly. Or at least, the least bad.
I also use Wayland because X11 had some lag when operating the desktop normally (I guess the pros call it “frame-pacing issues”?), whereas only XWayland programs will flicker for my NVIDIA GPU. And games aren’t part of that category. I don’t use a lot of XWayland applications anymore, so I actually haven’t seen the flickering for a while. The Steam client is the absolute worst, but… I’ve been doing my gaming on Windows lately 😬