... How stuff like plasma-desktop and plasma-workspace came to be removed I don't know. the was no hint during the DU and I never saw them being removed.
Have on an i386-system since some days hint for removal of those packages, so I didn't dist-upgrade. As of your post, I'll probably try to let them go and reinstall...
...Die folgenden Pakete werden ENTFERNT:
breeze frameworkintegration kde-style-breeze kde-style-breeze-qt4 kinfocenter libkf5style5 plasma-desktop plasma-integration plasma-widgets-addons plasma-workspace sddm-theme-breeze...
Complete Output:
https://ptpb.pw/OO8z