Need input, not enuf info to do anything with. I can say they need your help fast.
Have you looked for bugs? I dont see any webbing, but at least a 30x zoom lens here, and look to the underside. Absolutely 100% contagious and will kill all. Then wait for you to plant again.
What is the PH?
What is the RH?
What are the temps?
What is the medium?
How are they watered?
What are you feeding? And how often?
What are the lights? And schedule?
What is the actual wattage of said lights?
etc. etc. etc.