Created attachment 153104 [details]
Video showing expected behavior few times, then bugged behavior on last spectacle close

I noticed situation that looks like bug, where sometimes GUI apps leave process without standard way to kill it other than terminating process. Applications that I caught behaving like that so far regularly: discover, spectacle
It's I swapped to linux full-time few days ago so I do not have much data, but I managed to get redundant steam and lutris application instances as well while using PC. I managed to find reliable reproduction for spectacle for now:

STEPS TO REPRODUCE
1. Press print screen button to get result in spectacle
2. Make sure checkbox that closes spectacle after copying to clipboard or manual save is checked
3. Press "copy to clipboard" button at the bottom of spectacle, so spectacle window shuts down

OBSERVED RESULT
Spectacle process doesn't end and stays indefinitely in system monitor, any further attempts to call spectacle window and close it via X button don't terminate its process. Killing spectacle process manually makes it behave normally again on closing X button

EXPECTED RESULT
Spectacle is removed from process list on close - it usually happens when closing spectacle via X button without triggering the bug before

SOFTWARE/OS VERSIONS
Linux: Kubuntu 22.04.1
KDE Plasma Version: 5.24.6
KDE Frameworks Version: 5.92.0
Qt Version: 5.15.3

ADDITIONAL INFORMATION
May need to tweak some spectacle settings so it behaves like in attached video. I definitely managed to get discover app stuck in same state somehow so it may be not spectacle-specific bug