Handel es sich um Kalzium oder magnesium mangel oder ist das ein Pilz

Calcium deficiency (not mobile) usually starts at the top of the shoots with spots, often rust/reddish points at the tips. The yellowing between the leaf veins is from magnesium (mobile) on the lower leaves. Are you working with LED and have you added extra calmag? Do the shoots have purple stripes? Calcium and magnesium under LED is always a good idea, especially if you're using RO water instead of tap water. With an infection, the leaves would droop, but it can definitely coincide with a calcium deficiency since the transport to the tips depends 1:1 on transpiration. Does your substrate smell weird? In hydro, you can smell it quite well; soil, I think, gets a bit heavier. H2O2 (handle with care) 12% 0.75-1ml per liter of water or microorganisms afterwards are a way to deal with infections. From the pictures, it's difficult to make an exact diagnosis.