Hilfe hab ich meine Pflanze überdüngert

Dont think you can do much at this point, damage has been done. Best to prevent this from happening next grow. Cause is probably overfeeding/overwatering.

Pull those off. Check your temps, check your ph, and make sure you are in range. That actually does look like calmag!

This looks like a cal-mag deficiency.

Same thing happened to my magnum auto recently. I overfeed and messed up my PPM ( which I never measure) and began seeing brown rust spots. The leaves have become brittle and crumble at the touch. Damaged leaves unfortunately don’t recover, even after you correct the problem. I picked some of the worst ones off- mainly because I fear them starting to cause mold issues if the start breaking down near or inside a bud. But never pick off too many or it could slow down your growth.