I’ve seen this problem here, just don’t remember where…

Check out the leaves on this Grandaddy Purple.
Outdoors
Soil is Timerline soil/with Black Kow mixed
Week 5-6 flower
Recent flush and added nite per Fox Farm outdoor grow chart. Next feed is two days
This came about only in the last few days
Thoughts

You got bugs somewhere most likely. Check underside of leaves with a scope

Through a scope, I don’t see any critters
but the leaves look a little burned up close.

Might be mold of some type. If so, treat with a dilute mix of peroxide/water.

Looks like bugs, you might not see them. Get some Captain Jacks and spray them. I can not always see them but I can see where they have been.

Looks like bug damage to me

Looks a thing called yellow leaf fungus ( it can also be brown or grey or white…)