My issue was that when run through XWayland, Krita would work only on the primary display (no concept of that in Wayland) with 0,0 coordinates. So, if I’m on a laptop, it would work only on the primary (laptop) screen, but not the external one. I have a script that reorganises my workspaces and makes the external display the primary one, then runs Krita. But it would never work on any other display, if I wanted to use that too, for some multi monitor setup.
I may want to try that again, perhaps that was some bug that was fixed. But I’m surely not going to use X instead of Wayland for Krita.