Looks like nute burn to me. I did it just after a repot and it looked the same(but without buds).

Try lowering the nutes just a bit, or try watering without nutes an extra time. Not a full flush just lower how much is in the soil by a little. MANY times I've read, it's almost always better to under nute, then burn them. So going a little weak won't hurt. Mine responded to lower nutes within a few days. then dropped the burnt leaves after a week.

However loosing leaves at the end of flowering is common. So wait on a more experienced person before blindly following me.
Vancefish Reviewed by Vancefish on . need help on yellow leaves and brown spots down center What is your experience level? (first timer Your Equipment: .1) Type and wattage of lights. 600w hps .2) Distance from tops? 8" .3) Reflector type? enclosed air cooled .4) Is there a consistent fresh air supply? yes .5) Do you have an exhaust fan and a circulation fan? exhaust yes circulation no .6) What are the bulb wattages, kelvin ratings, and schedule? 600w 12/12 Rating: 5