Font display bug – garbled font weirdness

InDesign 16.4 on macOS Big Sur 11.5.1

When flipping through pages I get this strange font display issue. See screenshots.
It happens randomly. Not on every page but at least once every 10 pages.

I can simply turn preview on and off or go to the next page and back to make the page behove normally again but this should not be necessary.

This happens with all fonts.
This happens every day.
This happens on my colleagues computers as well. They are running various versions of indesign of various version of MacOS.
This has been happening in at least the last three or four versions of InDesign.

And, yes, we have tried resetting preferences, restarting, reinstalling, etc

Any explanation for this stange behaviour?