What should you do in this situation?

Your answer is correct because in this situation, you see a pedestrian in the mirror who may want to cross the street, and there is limited visibility due to the buildings and the parked tractor. According to German traffic rules, you must reduce your speed to be able to react in time and be ready to brake if the pedestrian steps onto the road. It is important not to continue driving as before because the risk of a sudden stop is higher here. Being cautious and prepared to stop ensures safety for both pedestrians and yourself.