And the main repos for Debian 13 has this mixture of KDE 5 and 6, and I think that's partially what's causing the problem, because my system settings looks like it's on version 5, and yet most of the modules installed are from version 6, and they can't see each other or talk to each other.

Understood. I have never been burned with GNOME, and I also prefer it—purist style—as it's integrated into Fedora.