Week 7.5 of flower and I’m seeing the tippytips of one of my plants browning. It’s only on some of the fan leaves at the tops of some stems

@Mr. Grow It the second video is the white light on. I Flushed either way. Trichomes are getting milky I’m going to do a 2 week water only and see how it goes. Runoff ppm was a bit high almost 3000 in the one plant but she looks fine. Other that those browning tips which I believe was the high amount of nutes in the coco.