Whats wrong with my baby

One of my autos sprouted and has some really light leaves compared to her sisters. What's up with it

It is very young but in my opinion and past experience, I would GUESS.... nitrogen deficiency because of the darker purplish veins and lime green/light grew color. Could be as simple as ph tho So the trouble shooting starts lol.

Wild; it almost looks like light burn... the way the parts of the cotyledon that aren't under the other leaves lighten too. Seems like a really unlikely answer, though...

About a pound

Newer leaves are always lighter. The older part of the leaf will always be darker. How old is the seedling and how fast are those leaves growing. I track that stage every day because them being so young, a lot can happen.