Who has priority here?

You correctly identified the red car as having priority. The key point here is the traffic officer’s hand signals. In Germany, the commands of a traffic officer override traffic lights and priority signs.

The officer is standing with one arm raised and the other extended horizontally. This means traffic coming from the direction you are facing (you and the motorbike) must stop. Traffic from the side road, where the red car is coming, is allowed to proceed.

Even though the traffic light shows green for you and the motorbike, and there is a priority road sign for you, the officer’s signal takes precedence. That is why the red car has priority and you must wait.

Remember: always follow the instructions of traffic officers first, even if traffic lights or signs suggest otherwise.