What is happening to my plant.

From the picture, your seedling shows some slight leaf curling and a bit of uneven color, especially in the new growth. That can be caused by: Overwatering → The soil looks like it might hold quite a bit of water; seedlings like moist but airy soil. Nutrient-rich (“hot”) soil Young plants can get minor tip curl or odd growth if the mix has too much fertilizer. Environmental stress Temperature swings, low humidity, or intense light can cause the leaves to twist or curl. Right now, it doesn’t look fatal more like early stress. I’d let the soil dry a bit between waterings, avoid feeding, and keep light and temperature stable. If it’s just environmental, new growth should look more normal within a week.

Salinity, the salt content of a medium (like soil) directly impacts directional water flow. Water will always want to flow in the direction of higher Saltiness. The tiny seedling exchanges gas, performing transpiration, this creates a pressure that draws water up the stems. Tiny seedling doesn't have enough oompf to counter the force of osmotic stress making the water wanting to go opposite direction due to salinity. If your seedling was a couple weeks older she would be able to push through it but it's like asking a newborn to go sprint 5km when she can only crawl. Just a little too much stress right now, leech medium a little. If she is older than 2-3 weeks and auto I'd restart.

If she's growing normally I would let it be sometimes they recover from hot soil.and sometimes they become your biggest plant but if you feel that it stunted rather do it

Soil is too hot...........fertilizing seedlings this size is a no-no when growing in quality soil for at least 4 weeks. Since it is an auto, you would be beter off starting again.

Thank that soil might be too hot for seedlings. https://youtu.be/xeSwrFKFNFw?t=100

Your soil is too acidic. Next time use light mix for seedlings and cuttings. If it's an auto I would start a new one.