AsNoriuanswered grow question a year 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.