If you hold the camera still for a little bit – don't move or look around – parts of the screen will randomly flicker. Usually it's the player's hand or item they're holding, but sometimes it's parts of the hotbar or even bits of the terrain. It's inconsistent enough that it's hard to reproduce on-demand, but it's often enough that I noticed and was a bit annoyed by it. So far I've only seen it happen in first-person camera mode.