Brown spots on seedling

Hello, Did you check for pest? Small bugs can nestle on the bottom of the leaves, and make dark spots. Could be over nutrition,the leaves will be fat and quite dark most occasions. Give it a week of tlc,without adding extra magic stuff, it’ll turn out fine I gues

Could have been from a bit of water splashing on them when watering. Could also be if your lights are to close. Led lights tend to make the plants use a bit more calcium.

Boa tarde, a mim parece me que tens um problema de ph ou talvez com a terra. Também pode ser humidade, nas fotos e um pouco difícil de identificar. Rega com agua regulada, vê a temperatura se esta indicada. Abraço