The White OG - indoor LED grow

Thanks for help trying to diagnose everyone. I know it's not nute burn or bad water because they are all in the same soil it's just FFoF I reused from some other plants so it should be less hot than it normally is. Shouldn't be PH either because they have all been watered together and this is the only one showing that much stress. The only thing I can think is I must have been over zealous packing the soil in on that one because its roots were growing out of the ground and pushing the whole seedling up so I tried to cover them with soil and firm it a bit to hold her up. In retrospect I should have just reported there or added dirt loosly to cover the root then prop her up with some wire. Anyway I think the compacted soil just held way too much water and didn't allow enough oxegen down to the roots