Potentially over-watered. If you initially saturated the soil when planting, it will take at least 5 days before it needs to be watered again. Lightly spraying the top of the medium once a day should be sufficient - if the top of the medium is dry. I hope it's not an over-watering issue because when they are that young it can take them awhile to recover; many growers just start fresh since a new seedling will mostly likely outgrow the stunted one.
I would def use it. Some people are against mixing it in water but It works for me then when transplanting I sprinkle on the actual roots and in new hole.
I usually add it once a week into my watering there isn't much proof on "too much mychroz" if you use recommended does.
But your Humidity was WAYYYYYY too high man. Refer to this VPD chart to stay with in range.
:) I had same issue and hey were curling and eventually fixed themself in a week.
Thanks I had the light at 24” now pushed to 30 temp was at 80 and humidity at 86.. now got humidity at 60 and temp at 79