I love KDE but I also sometimes feel like using Cinnamon, LXQT, XFCE, even Gnome if the moods strikes me. But often it seems like kwin starts when I am using another DE, the panel appears over other panels and generally things do not end well. Is there any way to keep that from happening?

On a related note sometimes kwin goes all wiggy and uses 100% of my CPU. I'll sometimes log out and log in to another desktop if "killall plasmashell & kstart5 plasmashell" don't work, but kwin will still be pegging my CPU. I often have to open a TTY and kill kwin from the command line. I use multiple monitors, if that matters, and a mix of Debian, stable and testing, as well as *buntu LTS.

How about some more details about your distribution and exact Plasma version?

The last time it happened I was on Debian Testing, bullseye, so I guess that is plasma-desktop (4:5.17.5-3). I can't complain about anything weird happening in Testing, since that is not a stable operating system, and stuff breaks too often. I'll report back the next time it happens in Debian stable or a LTS version of (k)ubuntu.