Description of problem:

I've been running CentOS 8 with KDE installed from EPEL happily for over a year.
Last week, I did a 'yum update', which brought a 2 GB download and took me to CentOS Linux release 8.4.2105. I also switched from nVIDIA to AMD Radeon graphics card.

Since then, my KDE desktop hangs randomly once a day. 'Hangs' means the following:
1) The mouse pointer is still moving happily, so it's not a CPU freeze.
2) If I'm accidentally typing in a terminal when the hang happens, I can continue typing in the terminal without problems.
3) But the rest of the desktop doesn't respond to mouse clicks or keyboard anymore. I cannot use Alt+Tab to switch to a different window. And I lose all open unsaved documents.
4) But I can switch to text mode with Ctrl+Alt+F1.. and log in there.

I switched from KDE to GNOME desktop, and there everything has been OK for the last week. But I would very much prefer to come back to KDE, which works much better for me.


Version-Release number of selected component (if applicable):

kinfoversion says:
KDE Plasma version 5.18.4
KDE Frameworks version 5.68.0
Qt version: 5.12.5
Kernel: 4.18.0-305.12.1.el8_4.x86_64 #1 SMP Wed Aug 11 01:59:55 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux


How reproducible:

I'm aware that things happening once a day are difficult to reproduce, but as written above, I can still switch to text mode, so I'm happy to attach the GDB debugger to anything you need and send a traceback, or do whatever else is needed. 


Steps to Reproduce:
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Actual results:


Expected results:


Additional info: