It's not necessarily derogatory, it depends on the context.

"Normie" just means "ordinary", "average", or "uninitiated". It usually means someone with very conventional political or cultural views but it can also mean "someone who isn't part of a subculture or group" ie developers talking about laptops might say "normies don't usually need more than 8GB of memory but some development tasks require more to be comfortable". Other times it's used in a more derogatory sense to imply that someone is a bit too credulous towards the establishment of the day ie "normies think that corruption and inequality only exist in developing countries".