So, I solved the problem by deleting the point and recreating it. Otherwise, it was impossible to animate properly. I think that from the beginning my model had a lot of those weird symmetry things going on, but since I was redoing my topology a lot, they disappear little by little.

better picture here. sorry

Hello Henrik,
I am not sure how to contact you. I finally managed to redo the bug.
I made an explanation here:

Hello Philipp,