Hmm, I can’t say I’ve seen that before. However, it might be worthwhile trying to just boot a live ISO of GNOME (or any other DE) just to rule out a KDE issue. Then if that doesn’t replicate the problem, try a live distro of something with a newer version of KDE (such as Fedora 39).
At the very least, that’ll help narrow down where the problem might be coming from!
I hate how installing or removing (or even updating) a flatpak causes the whole software center to completely refresh, and it doesn’t keep its state so if you were in the middle of a search or scrolled down through a category… say goodbye to it.