Can anyone identify this problem

Anyone know what this is? it is not a cal or mag deficency. I just started 8th week of flowering. i maintain 5.8 ph and use fox farm to a T. I recently started molasess in my ebb n flow and flushed last week. Im thinking this is nutrient burn at its bet. but i also think maybe rust disease???? my EC is 2.3-2.5. Not all plants are affected by this and for the most part they look extremely healthy. Usually i would do nothing to fix this and let it run its course. Im a strong believer of letting the plant get what it needs in its reserves and to press on with regular schedule. But those leaves are CRISPY.

No one? No one has anything on this one?

looks like a type of insect had that problem once but when i got mites under control it went away too so i assumes an insect.not a pro tho

look on underside of effected leaves and im guessing where its disclored looks like chunks missing on underside like something ate from the leaves

yea its not a mite/insect problem. Been over the leaves with a scope. im thinking it could be nutrient burn. im not quite sure though. next week im due for a flush. I change res every week and my ppms avg 2.1-2.5 ec. Healthy buds though.

looks like it could be blight fungus spotting on the leaves