I've noticed a strange issue for a while now where if the mouseover 'magnify' effect is applied, triggering it causes various program windows to flicker. I can't figure out common factors, since it happens somewhat inconsistently regardless of mouse speed and program focus. I saw this post from over a decade ago that sounded similar:
https://forums.winstep.net/phpBB2/viewtopic.php?f=2&t=2938&p=8650&hilit=magnify+flicker#p8650
However, changing dock transparency had no effect.

That sounds like a video driver or hardware issue, sorry. Especially if it is intermittent.

What are your system specs (Windows version, GPU, CPU) ?

Also, whenever we're talking about visual artifacts a video uploaded to Youtube or some other media repository site is always welcome.

For some reason I can't recreate it for a video right now, but I'm running Windows 10 Pro (Build 19045) with a Ryzen 7 2700 and GeForce GTX 1080.

Okay, finally caught one in the wild. Here's a video showcasing it happening with the dock settings window:
https://youtu.be/W8X0VmQjNvc

Thanks for the video. That actually looks like a video driver/Windows issue, sorry.

Notice that the dock itself does not flicker. It is up to the Windows DWM (Desktop Windows Manager) to fully compose the desktop image before sending it to the screen, so that issues like that do not happen.

Oh well, at least it's not constant. Hopefully whatever is causing it gets patched at some point. I have to wonder if any AMD users have experienced something similar.