One of the tricks Debian team does is they first compile the old KDE with newer libraries, then migrate KDE itself, like Intel's Tick Tock. This gives both a performant and issue-free experience as far as I can tell.
Note: I run Debian Testing on my Desktop systems. Servers always run stable.
Don’t get me wrong, KDE is a nice desktop in many ways, but it would benefit considerably from attention of a professional UI designer.
I currently use niri but Plasma has always been my go-to/backup DE. I always have it installed in case someone else has to use my PC.
I know, of course, that it's an extremely minor thing, but it felt quite representative. It also reminded me that Linux is stuck in this bygone age where it's expected for a computer to be a multi-user system, so of course they can't have a "privileged" user account other than root (and god forbid you'd think of using root as your normal every day user).