Looks like a Qt bug. I’ll fix this in the next build; the following in the debug console should fix it for now. You’ll need to reconfigure your columns afterwards.
del mw.pm.profile["editorHeaderQt6"]
del mw.pm.profile["editorNotesModeHeaderQt6"]
https://docs.ankiweb.net/misc.html
(edit: I had the wrong keys; I’ve edited the post to correct it)