Heater Bed Temperature is increasing without heating

[hcet14]

I agree with Sineos, I also would consider the printer unsafe to use.

Jonas, your Klipper installation is dirty!
Have a look here How-To Trouble-Shoot

@Sineos

If you see the message dirty in the log, your Klipper installation contains unknown modifications. Remove them / make sure you install a clean Klipper from the official source

My feeling is, it is caused by a SW and not a HW problem.