macOS 14.4. Mac Studio M1 Ultra over DP to PG38UQ monitor at 4K@144Hz. Just got this Mac Studio so can't say if the issue existed before.
Happens in stand alone mode, or as a plugin in REAPER, Logic Pro, Studio One... all latest versions. Only happens with NI products (tested with Komplete and Kontakt). Tried Superior Drummer, Diva, a couple Arturia plugins, some DAW stock plugins... no such issue.
EDIT: The below is supposed to a gif demonstrating the issue, but doesn't appear to work. Anyway, when I move the mouse the bottom 4/5 of the screen flickers black.
EDIT: Here's an Imgur link: https://imgur.com/a/kYYDT73