Sorry, my bad - the System Settings user accounts editor doesn’t edit the .face files, and I think this whole thing is now deprecated.
The system should use the org.freedesktop.Accounts System D-Bus API, which is what the user accounts KCM is doing. SDDM apparently still trusts .face files even though nothing has been touching them for a while.
You should remove the .face and .face.icon files from your home directory and instead rely on the Users KCM and the D-Bus service.
BTW - you can see what avatar the Accounts D-Bus service has for you by running qdbus --system org.freedesktop.Accounts /org/freedesktop/Accounts/User$UID org.freedesktop.Accounts.User.IconFile - it should output something like /var/lib/AccountsService/icons/USERNAME and if you open it with an image viewer - it should be the icon you see in the app launcher menu, the users KCM and - if there are no .face files - the SDDM login screen.