first grow , what is this on the leaves of my arjans haze plants

what is this yellow stuff?

looks like a nute problem but not too serious yet need better photos though to really see. make sure there isn't any spider mites on the bottom of the leaves just to be sure. they leave yellow spots all over the leaf though. but i am not really sure what is your soil mixture consist of???

soil is pro mix HP, no there is no spider mites im sure.

yeah it could be nute burn flush em you might want to tone down the mixture since thats the only place it could come from promix has no fertilizer

Nute burn.
Same happened to me on my 1st grow.
Flush and reduce nute concentration.