AsNoriuanswered grow question 2y ago Too cold , direct wind or overwatering with a bit off ph.
Fresh rapid grow is always  lime green, in few days going into darker green, thats very normal.
Top curl reminds overwatering a lot. Buts its coco, so only 3 options
Wind damage
Light too intense
You way off with ph, by look would guess higher  than should be. Low ph after few hours comes up with burn spots.
Ph meters even most expensive  brake or lie.