Glitch effect during cutscene
Since „Glitch“ is one of the hints this might have something to do with the puzzle.
During my playthrough there was a cutscene that had a split second glitch effect, it was right around the time when Zeno asked Grace what the password for Elpis is. Now I‘m looking for it on Youtube but can‘t find it, so maybe it only triggers for some people? Maybe there are other cutscenes that have this effect happen for other people?
It definitely wasn‘t a real glitch from my graphics card, it looked artificial.