I should write 100 times: “I will run a design rule check next time”.
The QuadControl prototype PCB arrived today. Unfortunately I changed the width for the power supply lines after routing them. Having a look at the design or running a design rule check would have shown that it now overlapped pins that should not have been contacted. But I did not run it before sending the files into production. Looks like this can be corrected by cutting some tracks and using additional wire, therefore the prototype can still be tested.