I see a lot of white specks on the fan leaves and that is usually a sign of spider mites and it also looks like a K deficiency. https://www.growweedeasy.com/cannabis-plant-problems/potassium-deficiency

Are you feeding it any kind of bud booster? 

I fought spider mites for a year and the only thing that works is NPK's Mighty, it kills the spider mites and their larva, nothing else on the market does that and you can spray a week or two before harvest and there is no health risk or bad taste.

1500 or 3000 lady bugs got their asses kicked by spider mites in my grow room, they ended up huddling on a light and dying a slow ugly death from shame.