SUMMARY
compositor displays a black screen when a maximized windows goes to full screen. 

STEPS TO REPRODUCE
1. Open an application, Firefox, VLC or konsole
2. maximize Firefox, VLC or konsole  
3. make that window full screen: press F11 on Firefox, on VLC open a video an press F to enter in full screen mode, on konsole right click on window title and navigate menu to full screen option.


OBSERVED RESULT

screen turns black, no image is displayed, only if the window was maximized before enter in full screen. 
NOTE: not maximized windows works fine.


EXPECTED RESULT

A normal fullscreen image of the window no matter the last size of the window 

SOFTWARE/OS VERSIONS

Linux/KDE Plasma: Manjaro 21.1.20
(available in About System)
KDE Plasma Version: 5.225
KDE Frameworks Version: 5.85.0
Qt Version: 5.15.2

ADDITIONAL INFORMATION

Operating System: Manjaro Linux

Kernel Version: 5.13.13-1-MANJARO (64-bit)
Graphics Platform: X11
Processors: 2 × AMD Athlon(tm) 64 X2 Dual Core Processor 4200+
Memory: 3.8 GiB of RAM
Graphics Processor: GeForce 210/PCIe/SSE2