Created attachment 141532 [details]
qdbus org.kde.Kwin

SUMMARY

I have attached a .mkv screen recorder of the moment I was having the issue. 
Occasionally several windows, if not all, becomes invisible, not possible to interact with (maximize or minimize does not affect them), task switcher and the screen corner effect of showing all windows also fails to bring any content forefront. At the video there are a few programs visible, however they were all opened after the problem started and no other instance were already opened.


STEPS TO REPRODUCE

I cannot systematically describe the steps to reproduce this problem I am having because it seems to occur independently of the program opened but the issue appears to be more frequent when I use the shortcut Meta+D to show the desktop and afterwards hover the upper left corner to show all windows.


OBSERVED RESULT

Invisible windows - please see the screen recorder video. 

EXPECTED RESULT

Window content visible. 


SOFTWARE/OS VERSIONS
Distro: Manjaro Kde
Kernel: 5.13.13-1-MANJARO
KDE Plasma Version: 5.22.5
KDE Frameworks Version: 5.85.0
Qt Version: 5.15.2

ADDITIONAL INFORMATION

Latte Dock - it does not seems relevant because I already encountered this kwin problem when Latte was not even installed. 
Plasma settings - the bug is present even after a fresh install. I tried switching the rendering backend from OpenGL 2.0 to OpenGL 3.0 and later on to Xrender but it did not matter. 
Distribution - Although I am currently running Manjaro Pahvo, I recently managed to get the same issue while using Opensuse Tumbleweed, Fedora 34 and Garuda Linux.
Plasma - I used Plasma for a very long time without having this problem, it started to appear with the release of the 5.22 version. I experimented with the most recent version of Debian and MXLinux and they do not show the same problem, I also believe that Opensuse LEAP will also work correctly due to the usage of a older plasma version. 
Xorg/Wayland - I mostly run Xorg but also encountered the visibility problem when trying Wayland. 
Kwin/Kwinft - The issue is present with both versions.