Looks possibly like an odd pattern of variegation. If that’s the case, then it’s normal. Regardless, it’s also my experience it’s normal to have slightly lighter new leaves emerging.
Normally you don’t see other issues like pH problems, nutrients, heat, wetness etc to show up like that at this very early stage.
Do you or have you had other seedlings that looked like this?
Agree with @VirginiaGrowBoy ,
also wondering if you are feeding them. Looks like Coco in the container. If so what are you feeding?
Looks like maybe some stress from something like overwatering, cold temps, or low humidity it’s hard to say without it being mine because I don’t know your every move… if that makes sense… just try to keep everything around it within the normal range and it should be fine, I have some going right now that I overwatered and they looked pretty similar to yours at that age… good luck 
My recent acquired clones arrived in soil-solo cups @ PH 5.5 and FULL DARK GREEN 4-node LEAVES.
While I am only guessing, your lack of green color might be Alkaline water/soil?
Yea some of the other seedlings look like this. They are hitting week 1 of veg today.
Currently watering every 2-3 days. They reach week 1 of veg today so when the soil drys up a little I will be feeding sho gun Terra grow
I’m running a 24 hour light cycle to keep my tent at 75F and humidity is at 65%. I learned my oh of my water was to low and I’m raising it next water.
That’s probably what it is then. The ph being off will make some nutrients unavailable to the plant which causes the deficiencies. I believe that is coco and I don’t use it so I’m probably not the best to give advice but I know it’s a little more picky about ph than soil is but way easier to get back in line when you are off
If that is coco u don’t wanna let it dry out keep the medium moist not soaked and wet but moist atleast. One good watering to get it all wet then daily a cup here or a cup there to keep it wet. If u can do it when u water shoot to have a 10 to 20% runoff meaning if u water with 1 cup try and get it to where u have atleast 10 to 20% of that cup come back out in runoff. This will help prevent the soil from building up any salts and stuff in the medium.