Feel like @Chris Scorpio is on target " like always"
What light you use and how far is it from your seedling
Are you keeping the soil moist ?
2 trick for that if you struggle to keep moist
1-Stop any fan if there are blowing on your seedling for the first stage till the seedlings feel strong and not flimsy
2- after your moist your soil put a little transparent cup with holes over the seedling to keep it moist if your gone for too long