Created attachment 134129 [details]
xrandr-output for the following scenariios: (1) both monitors are turned on (2) secondary monitor is turned off (3) primary monitor is turned off

SUMMARY
When physically turning both of my connected monitors off and on again, the only panel I have on my desktop moves from the primary to the secondary monitor. The only way to restore the original panel-arrangement is to log off and then log in again.


STEPS TO REPRODUCE
1. Have two monitors connected and turned on which behave the same as my monitors do (see below)
2. Make sure you have only one panel on one edge of your desktop so you can clearly see which monitor it is on 
2. Turn both monitors off
3. Turn both monitors on again

OBSERVED RESULT
The panel moves from one monitor to the other which cannot be reversed unless you move it manually or you log off and then log in again.

EXPECTED RESULT
The panels shouldn't move at all or rearrange themselves correctly as soon as all monitors are turned on again.

SOFTWARE/OS VERSIONS
OS: Arch Linux with up to date packages
(available in About System)
KDE Plasma Version: 5.20.4
KDE Frameworks Version: 5.77.0
Qt Version: 5.15.2

ADDITIONAL INFORMATION
My primary monitor is called Dell U2417H, my second monitor is called "ProLite E2280WSD". When turned off, they behave differently as it can be seen on the attached image.

This is my first bug report I ever submitted and english is not my native language, so I apologise for any mistakes I might have done.