This is not a duplicate post as there is nothing relating to Ubuntu Studio that I can find that actually works with this issue.
After a failed upgrade from Ubuntu Studio 21.04 to 21.10, I ended up having to use boot-repair
to get it to boot once again. It is clearly still Ubuntu Studio but the bootup splash screen says Xubuntu and all the login and desktop screens are something else too with something like the outline of a squid on them. How can I restore the proper desktop? Is there some command to run that will do it? Apparently this release includes Plasma 5.22.5 and the theming uses the Materia theme and icons are Papirus icons.
sudo dpkg-reconfigure sddm
shows
gdm3
lightdm (as the current)
sddm
sudo apt update
does not show any any hirsute and sudo apt full-upgrade
runs without any errors.
Ubuntu Studio (for those who don't know) is no different than Ubuntu other than it comes pre-installed with a full suite of multimedia and graphics applications.