KDE plasma freezes unexpectedly

I have Kubuntu 22.04.2 LTS. In the past few weeks, KDE started to 'freeze' occasionally. Is this a known issue? Is there any way how I can gracefully close/restart just the UI from terminal?
But most important, what should I check to collect some useful logs or details that could help to determine the cause of the problem?

Detailed description:

KDE just gets stuck, and I can not do anything in the graphical UI. It seems that this usually happens when I switch desktops or even windows on the same desktop, but I cannot reproduce the behavior on-demand. I can move the mouse cursor, the music is still playing in the background (clementine - and I can control it via keyboards shortcuts), I can log in to the console using Ctrl+Alt+F1, I can log in via SSH, but I can not control KDE anymore: I can not move windows, switches desktops, close windows, opening apps or anything similar. Once this happened during a Skype call and the call was not interrupted and I was able to communicate.
This started to happen only few weeks ago, it hasn't been happening before. I haven't installed any new hardware lately.

Technical details that might be relevant:

I have 128GB of memory overclocked to 3600MHZ, but I have had it like this for 3 years without an issue. Also, memtest seems ok -- memtester 1G 10.