NL / Zkittlez Auto seedsmen

We see this often no idea what it is but unless something develops which it never has, Just relax and keep half an eye on it.

Light burns, have just seen some on my plants and I think, oh I can tells that to the guy on GD 😂✌️🏽

First glance it looks like light burn to me. Could be overwatering but your leaves don't look too droopy. Since you have a Mars Hydro 600W at 24 inches I would not expect this but the foliage indicates lights should be higher in my opinion.