I managed to solve the problem with layering to keyframes with the same value and the same position over each other.
Now there is no space for a bump.
But I still do not know what actually caused it.
Problem fixed anyway! Thanks again!
Thanks for your answer, but as I only adjusted the Y-position and only the Y-graph has the problem, there can not be a problem with X and Z.
Just to clarify, I had a perfect linear graph between to keyframes. Then I put a nother keyframe on the gra…