Where does that spot come from?

It looks like the good ol nitrogen deficiency

Interveinal necrosis is a more advanced and severe stage of damage that often follows interveinal chlorosis. Most likely from excess Calcium causing lockout. If it was nutrient def alone it would present it's mobility. Incorrect pH causing lockout or calcium/potassium antagonizing magnesium causing lockout. Could also potentially be overwatering but that's easy to guague. If a nutrient lockout or high salt content is suspected, flush the medium with pH-balanced water to reset the nutrient balance.

Looks like the good old „Cal/Mg def-problem under led“. Best way to: add the right amount of cal and mg and get lower humidity in veg. Sunlight has made a study of this, you can find it on YouTube

This is Mg deficiency. You need to dim your light a bit and preferably add 0.3g of Epsom salt dissolved in the watering water just once. You won't be able to repair the leaf damage, but you can contain it so it doesn't spread. The reason for this can be varied - you need to figure that out. It's often not due to missing nutrients in the substrate. Usually, pH fluctuations, root stress, or general environmental problems are the cause. I just experienced something similar with my papaya plant. It was most likely because the light was too strong during the day and at night the VPD dropped too much because the temps crashed. With a lot of light (also relatively high VPD), the plant consumes more nutrients, and at night it couldn't keep up with the low transpiration.