Created attachment 142654 [details]
Blurry window example

SUMMARY

When resuming from sleep out of focus windows are all blurry and unreadable.

I have attached a screenshot to show the issue, the image is taken with the immediate option in the screenshot program, otherwise the windows are in focus, i don't know if kwin changes behavior if it detects that a screenshot is being taken.

The lower left of the terminal shows what the window should look like when it's in focus, as it appears to be in the middle of rendering the effect on that window.

The problem doesn't exist on login, only after suspending/resuming.


STEPS TO REPRODUCE
1. Suspend system
2. Resume system

OBSERVED RESULT

On resume windows fade in and out of focus, the active window will phase back into focus as the background windows blur so much that they are unreadable, the blurring doesn't look intentional, the text is being pixelated so the effect is not a smooth blurring.

EXPECTED RESULT


SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: Debian GNU/Linux unstable
(available in About System)
KDE Plasma Version: 5.23.0
KDE Frameworks Version: 5.86.0
Qt Version: 5.15.2
Kernel Version 5.14.0-3-amd64
Graphics Platform: X11

ADDITIONAL INFORMATION

$ glxinfo -B    
name of display: :1
display: :1  screen: 0
direct rendering: Yes
Memory info (GL_NVX_gpu_memory_info):
    Dedicated video memory: 8192 MB
    Total available memory: 8192 MB
    Currently available dedicated video memory: 7439 MB
OpenGL vendor string: NVIDIA Corporation
OpenGL renderer string: NVIDIA GeForce RTX 2080/PCIe/SSE2
OpenGL core profile version string: 4.6.0 NVIDIA 470.74
OpenGL core profile shading language version string: 4.60 NVIDIA
OpenGL core profile context flags: (none)
OpenGL core profile profile mask: core profile

OpenGL version string: 4.6.0 NVIDIA 470.74
OpenGL shading language version string: 4.60 NVIDIA
OpenGL context flags: (none)
OpenGL profile mask: (none)

OpenGL ES profile version string: OpenGL ES 3.2 NVIDIA 470.74
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.20