I'm thinking wet feet from poor drainage. The big fans on the bottom look like nitrogen toxicity but they also look bumpy and droopy from too much water. I don't think you said soil or coco. If soil, is it a good cannabis soil? It doesn't look like much perlite either. If you can't get them to dry out you may have to consider a transplant into smart pots with perlite and new soil. If you are already in flower stage, it's a tough call.