KDE's Dolphin on Gnome not working

My retired mom really likes to use KDE’s Dolphin over Gnome’s Nautilus. Eye roll On Fedora 39, I just installed Dophin, and it worked great. Then I recently upgraded her (by a fresh install) to Fedora 40. Now, Dolphin opens the first time after install, but doesn’t draw the window on second launch.

I already submitted a bug to KDE ppl for this. They suggested I try it under another user, then try uninstalling/reinstalling, then try to use a Dolphin flatpak - none of this works, and I’m getting no window drawn on second launch. The workaround that works is to delete .local/state/dolphinstaterc file, and then the window opens normally, but with allllll the settings reset to nasty-looking defaults.

It really feels like a Fedora bug, not KDE issue. Anyone has any ideas or suggestions. What could this problem be caused by?