Shed B.B. 4, top pic...looks like what I experienced in past grow, & with Luna. Dampening off is what I decided it was. See at the base of stalk...how thin it gets, it may keel over eventually & need support. Def let it dry out aerate around it as much as possible. I just realized you're in that cube thingy, so not much you can do to dry it out. Maybe as much direct breeze as she can take. Luna is bouncing back a bit I think, so yours will to my friend!!
Also, I was able to raise soil level to just below the cotylodons. Helped keep her upright, & I was thinking it might help dry up the moist soil, by putting dry soil on top. Have no idea what, when or why, but something helped Luna back, as well as the 4 I did that too over the summer. They all fell over in dirt, and were dry & pinched looking at the base. A couple of them are also curved like a "j", when I moved gently, the soil at base of their stalks. They were stunted due to lord knows what, but they all got this same treatment, & all pulled through. So just my 2 cents broskadeen!! Great day!!