Yellowing

it can be a slight nitrogen deficiency or an error with the pH of the solution you give to the plants

Your lighting is very powerful. raise the lamps or, if not possible, reduce the power, the plant is stressed and does not feed. First of all, you need to solve the problem with lighting. If you leave it like that, then after a while you will see a test on the leaves. you see how the plant raises the leaves at a large angle

Yeah, I think it's a nute burn (dark green leaves+red stems) so give them only water for few days and see. Check for pH in and out :)

Substrate and feeds being used of GH? I’m not seeing much in the pics. My guess would be slight overfeeding tho and you’re getting some yellowing tips up top from it