I don't know if it's a bug or I have miss configured something but it just cost me 20€, A lot of work and my printer is now damaged. The problem is the following;
After a print is completed (not the print job in Repetier) it tries to rehome the z axes resulting in the hot nozzle destroying my part. I observed this once before on a calibration cube and thought it was just a bug in my g code (Because it did not happen the next 10-15 prints). Then I printed a large part today and it smashed itself in the part luckily I stopped it before it got worse and bend the axes. Because I powered off to stop it the "Retten" feature turned against me and instantly tried to rehome xy resulting in even more damage. (Also the "Retten" feature has a bug where even if you press the STOP button it tries to rehome again). I did not configure any custom gcode in Repetier server also I observed the gcode from my part and there was nothing about rehoming z axes.
As a slicer I use Cura (4.6.1) with the Cura plugin for Repetier and I attached my Repetier Firmware and the GCode.
(I used Octoprint with the exact same setup before so the bug must have something to do with Repetier server)