Why are you required to stop now?

You answered correctly: The reason you must stop in this situation is because of the tram. In Germany, trams have special priority rules. When a tram approaches and there is a stop sign or it is clear that the tram has the right of way, other road users, including cars and bicycles, must stop and let the tram pass—even if you are on a priority road. Neither the cyclist nor the yellow car are reasons to stop in this scenario. Remember: Always watch for trams at intersections and be prepared to stop if a tram has priority. This ensures both safety and compliance with German right-of-way rules.