Light to close?

Combination of both magnesium and phosphorous deficiencies.........also possibly too wet for too long..........over watering/watering unnecessarily.

Hey there don’t worry I know what’s going on When plants are small their leaves are very sensitive if you over water just a little bit and the soil sits wet for awhile the early leaves will do this also overdoing lighting or to much wind directly on seedlings can cause similar problems I would say it’s over watering thou the leaves being soggy and those brown crisp spots are all signs of over watering. Make sure to let soil get really dry between watering during veg

It does look like light stress (possibly combined with some heat stress). You could try raising the light a bit or slightly lowering the intensity to see if new growth looks healthier. If it continues, also check your feeding – sometimes early calcium issues can look similar.

Looks like low potassium (The look of the tipp of the plant is more important than a single leaf). If you already feed nutrients, try to check ph of the solution.