The ffmpeg update from packman removed the Plasma patterns…when you said “yes” to the zypper dup you got kicked out of the session and dropped into an IceWM login screen…
Start IceWM
open YaST software
list the packages from packman repo and switch them all back to OSS repo
install patterns-kde-kde_plasma and patterns-kde-kde
logout and chose Plasma session
go into systemsettings “Login and Logout” and chose a theme for SDDM to have SDDM back…