Square Lights

[DementedCorn327]

There is that similar topic but related to AI aircraft:

Square looking navigation and strobe lights on AI planes

The nav lights on AI planes when observed at a distance appears as red, white and green squares and looks very bad, especially at 4k or for those who run at higher resolutions other than 1080p. They look like oversized pixels and they shouldn’t be a single solid color. I took a few pictures to demonstrate the problem. [square_nav_lights2] [square_nav_lights]

Not sure if I understood your reply, have you tried in safe mode ?
Can you show a screenshot with a base MSFS aircraft like C152, C172, C208 ?