Nute Burn?

Just needs water and nitro

Yep, new soil + extra nutes + baby plants = burning. New soil + baby plants = ok. Why have big bags and only half fill them by the way?

Oh if its just top feed and you have not watered much then you might be able to remove the top couple inches and replace with unfertilized mix. If you have a PPM/EC meter then testing runoff would tell you if you successfully removed the excess amounts..

I would guess nutrient burn. Most manufactures recommendations are to strong for baby pot plants. Also you have them in 7 gal bags, But it looks to have around 2 gal of space left, So I would say you only have 5 gal of medium. Its best to always start light and increase as you can always add more but its much harder to remove. I would re-plant them in a reduced strength mix of only 3tbsp( 2 gal dose ) mixed in to the 7 gal. And top feed when needed. Good luck and happy growing

did you transition these to the sun or just put them in direct sunlight? could be part of it. recent transplant? could be hot substrate? you'd know better on that. looks like high potassium or salinity (if poorly processed coco, these things increase in probability), and if pH is out of whack or there's an imbalance of nutes, could be lockout which means anything is possible. more info needed to give you a proper answer.. maybe thise strikes a chord and you figure something out too. you can look at a leaf chart and match up the symptoms as well as i can, but there's more to it than that. data, data, data needed for rational conclusion you can depend on