After a disastrous update for my kde “testing” desktop, I had no choice but to re-install Kde as the “standard” version. Works fine but I noted that the stable branch update take a long time to be updated and getting the latest development. I made a backup and switch directly from stable to unstable. Surprisingly, there was not much happening but I am now on Plasma 6.5.1.
The only “minor” issue is that all the icons on the second monitor have move to the primary screen and refuse to be moved again to the secondary screen. I check every setting and they are not locked but no icons can be created or move to the secondary screen.
Great find Kostiantyn ! That’s the exact issue. Not sure if it is a new “feature” but like with that problem mentioned in your link, the “disposition” has to be toggle from “Folders view → Desktop view →Folders (default)” view again to fix it. Sadly, it doesn’t stick after a logout or reboot, as mentioned too. You have to do the same thing again. Anyway it is a known bug now for them.
Thank you very much for the quick help. Appreciated !
. There are some tips directly from the KDE developers on the forum that might help: 
