Created attachment 142538 [details]
A video of the observed behaviour

SUMMARY
I just updated to Plasma 5.23 and tried the new effect. When using 1 monitor everything works just fine, but when adding a second monitor, the overview on the second monitor is completely broken, also the search only works on one monitor even if I explicitely focus the other one.

STEPS TO REPRODUCE
1. Add a second monitor (just open the lid of my docked laptop)
2. Press Super+Ctrl+D

OBSERVED RESULT
The overview is broken in the second monitor, with flickering and weird dimming, also the search only works on the broken monitor.

EXPECTED RESULT
A nice overview should appear on both screens, without dimming the background nor flickering, and the search should work either on the focused monitor or on both at the same time

SOFTWARE/OS VERSIONS
Operating System: Arch Linux
KDE Plasma Version: 5.23.0
KDE Frameworks Version: 5.87.0
Qt Version: 5.15.2
Kernel Version: 5.14.12-arch1-1 (64-bit)
Graphics Platform: X11
Processors: 4 × Intel® Core™ i5-3320M CPU @ 2.60GHz
Memory: 7.5 GiB of RAM
Graphics Processor: Mesa DRI Intel® HD Graphics 4000
ADDITIONAL INFORMATION