Adam, the wayland backend is enabled only when Wayland session is active. KDE does not use Wayland session on Fedora 32/33 so X11 under KDE may be used here. I suspect you see WebRender bugs as WebRender is enabled by default on KDE too. You can set gfx.webrender.force-disabled to false at about:config to force disable WebRender.
Can you please file a bug at bugzilla about the failures and attach a screenshots there? Thanks.