def got some bug shit there. maybe gnats though. do you see any webbing? or little bugs walking around? take a scope to your leaves and see what you can see mites are pretty easy to spot with a good scope or loop
i don't see any damage , like cacamal said look under a scope and you'll know for sure on top of the leaf like that it looks more like something that has just drifted into your grow room like dust or something