I think it’s signs of low O2 at the roots, the result of overwatering. Actually the growth tips are starting to look a little perkier in this photo so maybe it’s recovering. I’d feel more comfortable diagnosing if someone more experienced concurs with my opinion, though.
Might be worth repeatedly pushing a dowel or pencil down into the root ball for added root aeration.
: What are the big pots sitting on? The seedling on the skil box appears to also be droopy, although overall it looks better.
Also, check out this page from another website: https://www.growweedeasy.com/cannabis-plant-problems/overwatering