It looks like a drag-and-drop operation from any KDE app does not complete correctly, which leads to the cursor then behaving strangely (see https://bugs.kde.org/show_bug.cgi?id=438004), and the drag-source application after that cannot terminate its work and remains stuck after closing. Running the drag-source app from the terminal gives no hints of errors.

I'm not sure which category I should place this bug in, so please don't judge strictly =)
I would be happy to help with reproducing this.

STEPS TO REPRODUCE
1. Start Wayland session
2. Run Konsole and Kate, for example
3. Drag some text from Konsole to Kate
4. Close Konsole
5. Open the System Monitor and make sure Konsole hasn't exited

Instead of Konsole and Kate, there can be any two KDE applications.


SOFTWARE/OS VERSIONS
Operating System: openSUSE Tumbleweed 20211210
KDE Plasma Version: 5.23.4
KDE Frameworks Version: 5.88.0
Qt Version: 5.15.2
Kernel Version: 5.15.6-1-default (64-bit)
Graphics Platform: Wayland