Seedling problem

Seedling in starter soil. Other seedlings are doing fine but this one and one other look fubar. Had stretchy stems that i replanted.
(looked odd before i replanted it)
If youve seen this before or have an idea of what it is Id like to hear it.

Looks like nute burn or some thing, but as the other one is alright perhaps this isnt true.

Ive recently had some problems with my seedlings and then in early veg, after stretching too much the stem went really thin and brown in the middle, the leaves started curling and turned crispy. the colour turned brown eventually and died.

have you looked at the stem below the soil? you might have gotten the same problem as me.

Def not nute burn, its seedling soil thats suppose to be low nutes and ive been using purified water because sometimes my tap water can be a tad bit hard.

Im thinking it had to do with stretching too much. Idk though

What the ph of your purified water?