Created attachment 142372 [details]
screenshot showing the black panel on system settings

SUMMARY

After sleep/resume 


STEPS TO REPRODUCE
1. Open system settings, click on "system information"
2. Click Sleep, to send the PC to sleep
3. Wake the computer and login again.

OBSERVED RESULT

The right-hand pane which previously showed the system information is now black.
Clicking other sections (e.g. audio) shows some info, but KDE connect or printers remains black
Clicking back to system information remains black again.

To workaround: resize the window, and the panel stops being black.

See this video for a demonstration https://www.youtube.com/watch?v=WAL3IV__HOo

EXPECTED RESULT
Expect to see system information, without a black panel

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: kubuntu 21.04 w/backports
(available in About System)
KDE Plasma Version: 5.22.5 
KDE Frameworks Version: 5.86.0
Qt Version: 5.15.2
Graphics platform: X11

ADDITIONAL INFORMATION
Nvidia RTX 2060 card, dual monitor configuration
Driver Version: 470.63.01