Google russet or broad mites.I don't think it's heat stress
I use 5ml per quart fuck it if it's tough. Better than bugs being on there during flower. Plus I didn't raise no weak bitches lolI use neem oil too - and it works but it's also pretty tough on the plants. I mix it at about 4 ml/quart. Being an oil, it doesn't mix into water - you need to use an emulsifier so that it will. 4 ml of blue Dawn dish soap works fine - it also helps kill bugs. Mix the neem oil and dish soap together, then pour into 1 quart of water and mix. Spray at lights out.
If you make it any stronger it will leave burn marks on the leaves.