White Flashing Alphabet

Does anyone know what causes this to quickly flash on the screen periodically during play, and do you have any recommended things I can try to fix it?

It doesn’t seem to matter what core I’m using, or what types of roms they are (MAME or Console or Homebrew).

It’s a Windows 10 x64 box with plenty of DDR4 ram and a sufficiently beefy Radeon GPU plugged into a 1080p 16:9 LCD TV over HDMI.

Video of the problem: https://streamable.com/qnn6nz

I’m not too experienced tuning Retroarch but I’ve tried quite a bit in good faith and nothing seems to fix it. MAME roms that exhibit this problem run fine in MAME, and sometimes I can resolve it by trying a problem rom in another core, so it’s maybe a rom/core compatibility thing? The only consistent thing is the symptom itself which suggests it’s a Retroarch-specific behavior when there’s something it doesn’t like about the emulation it’s attempting.

Anyway, thanks in advance for any pointers.

Update: This appears to be linked to the use of an overlay. If I disable overlays, this artifact disappears. Should I submit this as a bug, somehow?