Why must you brake now?

You were correct in selecting the cyclist as the reason to brake. According to German traffic rules, when passing a cyclist, especially in urban areas, you must always maintain a safe lateral distance—at least 1.5 meters, and sometimes more if needed for safety (§5 StVO). If the space is tight or the cyclist may swerve onto the roadway, you are required to slow down or brake to ensure you can pass safely and avoid endangering them. In this situation, neither the red vehicle nor the bus stop presents an immediate reason to brake, so only the presence and position of the cyclist require special caution and possibly braking. Recognizing situations where vulnerable road users could be at risk is an important aspect of defensive driving in Germany.