Created attachment 132196 [details]
Bug picture

SUMMARY
I have two monitor. One the laptop's builtin another external monitor connected via HDMI. They are both the same resolution (1920x1080), the latter one being the primary monitor. The placement its coherent within boots, where the builtin one is on the right and the external one on the left. 
But at every startup i have to misplace them and then replace them because weird things happens. I have a panel on the primary monitor, and at every startup the app launcher and the app previews show on the non primary monitor at my right. Only when i misplace and replace the thing is fixed but its very annoying, because this also mess with the app launcher configs. 

STEPS TO REPRODUCE
1. Have a dual monitor and a panel on the primary
2. Reboot
3. Cry a bit

OBSERVED RESULT
The attachment shows how the app preview shows on the monitor on the right

EXPECTED RESULT
The things being showed on the primary monitor


SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Kubuntu 20.04 but happened in other distros as well
(available in About System)
KDE Plasma Version: 5.18.5
KDE Frameworks Version: 5.68
Qt Version: 5.12.8

ADDITIONAL INFORMATION