Screen goes black for ~3 seconds sometimes during a match

As per title:
I play a match and the screen may go black for say 2-4 seconds. Usually in the middle of a match. I don’t drop to desktop while the games runs on fine and I could swap back right away (this did happen sometimes in the past). I just lose the screen - it goes black. After the 2-4 seconds, I just play on as if nothing has happened. No crash or anything, just a blackout.

I read about a change regarding Steam overlay, but I don’t use it and I don’t have steam running.

Any idea what this could be?