What are you feeding? How big of pot are they in? They grow quick and fill up a pot quick. use a lot of nitrogen right now too
Edit: I had that same problem. Translated into larger lots and it helped some then increased my nitrogen and it took care of the problem. I’d get a PH reading too, runoff
check the last of ur runoff ph. if u have a slight calcium deficiency it may be caused by out of range ph. ive been working on my runoff ph and it has been routinely taking about 50ml to balance the naturally acidic soil of ffof
Looks like they’re in solo cups. I would think those roots need more room.