Why was I penalised for hard braking when I couldn’t avoid it?

The app does not know the circumstances of a specific hard braking event – it only measures how hard you are braking, and for how long. Your overall score takes into account the number (rate) of hard braking events. Occasional hard braking in unavoidable circumstances does not substantially impact your score. Note that you may lose stars for an individual trip because the stars only provide a measure of what happened on that trip.