I have the same artefacts. Only a few people were complaining about it in other threads. Hope it will be recognized by the devs. It gets worse over time. In the beginning of a flight, I don’t have artefacts. But later, I do. Especially when I’m panning the camera around.
Similar issue can be found in this thread: Glitchy Pixels at top of screen - Bugs & Issues / Install, Performance & Graphics - Microsoft Flight Simulator Forums