Ich benötige bitte Hilfe bei der Identifikation von Symptomen an den Blättern

It looks like a nutrient lockout due wrong pH or too much build up salts and nutrients inside the soil. Next time you water give till 20% runoff to prevent salts and nutrients building up inside the soil causing wrong pH and EC inside the soil.

the one leaf looks to have no progression of the blemishes from week 3 to week 4. so, i'd chalk that up to an early 3-fingered leaf being a bit fugly. no big deal interveinal chlorosis could be progressing, though. several things can cause that. you look to be in hydro/soillles, so start tracking your nutrient ppms, not just overall concentration. ratio as well as concentration is important. you have to consider too much of certain things too. for example, too much P will result in lockout and cause interveinal chlorosis (zn, fe, mg) and spots related to both ca nd mg. it's an interconnected web. check out mulder's chart. it can help when making adjustments or diagnosing. a good leaf symptom chart should include these relationships / mention them. once it's all dialed in, don't have to track the ppm's so much. and if using same products, you'llknow by corresponding dosage by that point. knowing ppms allows easier change over to another product of different stock concentrations too.