Curious if anyone else has run into this, as I played through the full game and both DLCs on PS4 a couple years back and don't remember this being an issue. There's an occasional graphical bug where shadows that are being cast on NPC faces start flashing between RGB colors at a high speed. So instead of a proper shadow on their face, I see a pixelated strobing effect that's extremely distracting. It doesn't happen all the time during every single conversation, but it happens frequently enough to become annoying and immersion-breaking.

It only happens to shadows cast on the faces of NPCs, never Geralt himself. I've only seen it happen on their faces, and it only happens during dialogue. I've never seen it while I'm in control and able to move freely.