I think it's probably time to consider this release blocking, with caveat. It's
been known for quite awhile that lingering processes makes user switching under plasma
problematic, so this problem needs to be solved first as a prerequisite. One possible
solution is
https://fedoraproject.org/wiki/Changes/KillUserProcesses_by_default
(but I don't insist on that particular fix, just that it is addressed somehow first).