Strange leave color

Looks like a deficiency or ph issue. Check your run off ph and probably flush to get rid salts. When flushing with coco don't use straight water but a weak ph nute solution with cal mag. I go about half strength base nutes. After flush return to feeding. Cut back slightly on nutes you were giving and start adding booster or more of booster being used to up p and k. If you just started flower or are in late flower it could just be plant using stored nutes from leaves as it uses more p and k so might work its self out.