I wouldn't freak out, looks like they are getting close to done. Leaves will fade out and may show burning as the plant finishes up. Different plants are sensitive to different things. I would trim the burnt parts of the leaves and possibly dial back the nute solution some. PH lockout, over and under watering as well as to high EC can cause similar symptoms. Finishing up I would aim for around 900 ec flush
@6 ph for a week.