What can be the consequence of your passenger (pillion passenger) on the motorbike not wearing conspicuous clothing?

You are correct in selecting that a passenger not wearing conspicuous clothing is more difficult to recognize for the following traffic. In German traffic regulations, visibility is important for safety, especially for motorcyclists and their passengers. If the passenger is not wearing bright or reflective clothing, drivers behind may not see them clearly, increasing the risk of accidents. This does not affect the traffic ahead or oncoming vehicles as much, because the passenger is mainly visible from the rear. Therefore, wearing conspicuous clothing helps ensure that the following traffic can identify both riders easily, reducing the risk of being overlooked. In future scenarios, always remember that visibility from behind is crucial for motorbike safety.