If you in coco with LED and you dont add cal mag 1ml per liter every feeding it does that ..my personal experience and i stopped using coco went back to peat moss and never stopped giving that 1 ml/liter cal mag every feed they love it !
also when they look sad like yours id say foliar spray them with a 1ml/liter calmag + declorinated water room temp 2 times per day, dim the light down tho, to not burn them , and watch them thrive after a couple of days.( with coco 1.5ml to 2ml per litre would probly be even better since coco breaks down calicium.
My 2 cent.