3 weeks old in soil, recently started to show signs that something is wrong. What do you guys think i can do to get her back to normal?

Just by looking at it, looks like magnesium deficiency. Have you been feeding in any CalMag? Also, do you know the pH and PPM of the soil runoff?

Their all in the same soil. So if one doesn’t have enough food would it be safe to assume all of them soon will need food?

That still does not do the job. Your plants grow is all about getting strong from the bottom up you should not have any problems like soil the seed and the soil have enough to last a bit longer. It sounded like you were only concerned about one plant?

Its just coast of main soil. I can put a little 444 and worm castings in? I have 6 of them so i feel they will all need the same treatment

no food just good healthy root protection let her grow a little more it isd a fast grower that is good but the micro balance could maybe use a boost since I don't know what all you have done veggies need to be strong not oversaturated with water or drugs.