I took another picture of the circuit exploding. So that you can see correctly that it is a defect and not a production hole. You can see the broken edges nicely. Since most stepper drivers have an integrated overload protection at too high a temperature or too high currents, only overvoltage is an option for me. I also see the danger with the fan motors. There, however, the stress may not be so great because there is no reversal of the direction of rotation and the load changes are not so rapid.
