burn or deficiency?

I think it's burn I watered last water with around 850 ppm solution maybe be to early for that high of a solution day 10 of flower in coco

Your other leaves look good. I would say it is a burn. I wouldn't worry, it looks like your new growth is doing well. What is the strain? Temperatures? How much fresh air?What lights, distance to light?

Sensi nl cns17 nutrients with other botanicare supplements I think they got burnt from a build up I medium which is probably from lack of drainage as I didn't add any grow stones so it's a 100 percent coco which I'm coming to find that I prefer about 20-30 percent growstones to give plenty drainage