What is the right course of action in this situation?

In Germany, when you approach a situation where a lane ends—such as the right lane merging into the left—you must adapt your speed to safely merge. Slowing down is the correct action because it allows you to adjust your position carefully, observe other vehicles, and merge smoothly without causing danger or forcing others to brake suddenly.

Maintaining your speed or accelerating when a lane ends can lead to unsafe situations, such as cutting off other drivers or losing control during the merge. Slowing down gives you better control and increases safety for everyone on the road.

In summary, the rule is: When a lane ends, reduce your speed to merge safely and courteously. This anticipatory driving behavior is essential for smooth traffic flow and accident prevention.