idk about the coloring but my guess is your over watering? have a seedling just like that membrane was stuck on for about 2 days since sprouted until i removed it. of the 3 it is the slowest growing one with some deformed first set of leaves as well but still growing. the leaves are not yellow. im growing in roots organic original soil, i water with just plain tap water not PH'd. the ONLY thing i've added to the grow thus far is Myko's in the granular form under the seeds when i planted them as well as Voodoo juice and thats it.
literally checked the roots on the biggest plant they are fucking crazy and starting to wrap around the solo cup.
1 thing i need to bring up though is; why are you misting?
here is my 2cents. 1. possibly over watering ( maybe stop misting them and water normally? and less often i water my seedlings so far every 3 days. literally just watered them 5minutes ago because i had to check the root system shit felts dry though after just 2 days now but i do run my lights at 24/0 ) 2. possibly soil is too hot or just bad in general? what kind of soil are you using? maybe others can chime in it doesn't look healthy though