I've got a control panel for sddm only after manually uninstalling the package 'sddm' and installing the new 'sddm-qt6' . Looks like 'zypper dup' didn't handle this during the KDE5->6 transition and left the user with a weird/ugly login screen. Took me 2 days to fix it, thanks to u/DragonOfTartarus on Reddit's opensuse sub.