Good grief. It’s already fixed, as noted in this thread.
This issue has nothing to do with KDE and everything to do with GTK4.
This thread is a duplicate of GNOME/GTK Application tooltips are stretched/distorted - #12 by Tekstryder and should be closed as such.
I’ll mark the tracking thread as solved when egl-wayland2 is officially tagged for release.
Currently on git main without issue.