seedlings leaves going yellow help plz

hi can anyone help please im new to growing my super skunk seed has started to go yellow with darker marks on leaves its 3 weeks old in soil under viparspectra 300 w ive enclosed a few pics if anyone can help id be so grateful

anybody got any ideas ?

Light distance and what medium actually is. Meaning dirt or peat. Nutrient enriched or not

That first one blade leaf is meant to feed the plant in the early stages after its grown some more leaves, it often goes yellow I wouldn't worry about it too much you're other leaves are dark green so it's not nitrogen deficient.