KDE Plasma 6 reboots on video playback

Since about Plasma 6 onward I've been getting system restarts when attempting to play back video files and/or seek through them.

The system will crash and reboot when:

• Attempting to play any video with an mp4 container (mpv and vlc tested)
• Attempting to seek with the mouse while playing most videos (mp4 and matroska)
• Scrolling too fast in a file manager
• Clicking and dragging to resize various windows (terminal, browsers, etc)

The system performs fine when:

• Playing videos in a webm container
• Playing videos in software like avidemux, kdenlive, gwenview, etc.
• Streaming video in a web browser

The issue has persisted through these toubleshooting measures:

• Update to latest BIOS firmware
• Switching between Wayland and X11
• Substitution of the PSU to a brand new unit

My assumption so far is that it's not hardware related. Currently I suspect it's Plasma. Below is the journal output of records around one such crash time of 5.19-5.20pm:

Suggestions for next steps would be welcome. Is it worth considering a rollback to the previous/older Plasma versions? Assuming Plasma doesn't like my DAC or keyboard or whatever, is it worth substituting or removing USB devices?