I see ur not using LEDs. Make sure your space isn‘t getting too hot. Anything above 25°C makes it hard for the seedlings to adjust their owntemperature. The lights ur using are not only causing heat but it‘s also very difictult to see anything under them. Maybe you would have noticed the burns earlier? I don‘t they they lack nutriens because a plant this young doen’t need much. I think the way the leaves are turning downwards it‘s more of a heat/light problem. Thats my opinion.