Any one care to take a look at the back left lady ...

Your day temps are very high and your light is quite close. You would do well to reduce both of these. I think it looks like one of fastbuds mutant seedlings, I had a very similar one in my green crack grow. You do need to start thinking about nutrients soon though. And they don't need much watering at this point they absorb through their leaves! 🌱👍

overwatering.roots cant get o2,root zone is too wet.give it some more waterless time,it'll recover.Looks like it has 3rd set of leaves like others but small pheno & overwatering combined and this the result.let the soil dry out.and watering outer parts of soil is unnecessary at the moment.only water where you think its roots reached.increase amounts as it grows.let it dry out for a few more days and newer growth will look better.very common problem.

I feel this is definitely an over watering issue and the girl is starved of nutrients, currently. She's not taking the nitrogen needed to keep a healthy green hue and this is when the yellowing usually starts. You made the right move by backing off the feeding. At this stage, localized watering is highly recommended, as there is no root system to take up excess moisture in the soil. Feeding lightly w/ 50-100ml, .5-1 inch away from the stem, once a day or so. Try to avoid watering any medium that doesn't have a root system as it will take a lot of time for that moisture to dissipate. I suggest adding a few extra small fans for air circulation and tilling the top couple inches of soil around the girl where there are no roots. This will dry the medium out much faster and allow your plant to breath and for roots to start tapping into new soil. This may take a couple days and the yellowing may stick around for a bit, but! it will stop when the she's able to breath and starts to take up nutrients. Namely Nitrogen. You're going to be A ok. Ive over-watered many times but it's a decent problem to have because it's easier to fix then other problems. I wish you luck with the girls and of you have any other concerns I can help you with, throw me a PM 👍😉

Hello my friend This may be due to overwatering. Unfortunately your photos do not allow for a more in-depth diagnosis.