Please help!!

Hey guys i need help my plants have stopped growing for a week and started looking real sad im not sure what's happening. Ill give u all the info

I started with cuttings from a mother Once they rooted I put them into 5 gallon fabric pots with promix and 20% per lite mix..I veg them 2 weeks in 2x2 tent under a cheap Amazon led 20 inches away they were getting around 250ppfd ( I have a par meter) and looked amazing.. temps 72f RH: 85

Start of week 3 veg I moved them to my big tent 5x5 under a spiderfarm 4000.. 40 inches away with a ppfd of 400 ..also with my co2 900-1200ppm , dehum n fans ect. Temp 75f RH 60. Since the move they have stopped growing vertically...some small new leaves..and started looking more n more sad by the day..can someone tell me what's going on? I try and feed Monday Wednesday and water only Fridays at 75 percent of recommend dosage..I did let them dry out for 4 days in case it was overwatering..I fed today 500ml each plant nute ppm was 580 ph 6 4....How can I save them? I'd appreciate any and all possible causes so I can narrow down what it could be ..thank you

Pic 1 day 15 veg (first day under spiderfarm)

Pic2 day 21 veg (1week under spiderfarm)