What is the right course of action?

In this situation on the German Autobahn, you are correctly overtaking a series of slower vehicles in the left lane. German traffic rules state that you must complete overtaking all slower traffic before moving back to the right lane. Even if another driver approaches quickly from behind and tries to pressure you to move over (for example, by tailgating or flashing headlights), you should not change your behavior—do not brake or move over until it is safe and you have finished overtaking.

Braking to prompt the car behind to keep its distance is both dangerous and not allowed, as it increases the risk of accidents. You also shouldn't attempt to overtake only some vehicles and move back and forth between lanes; the overtaking maneuver should be finished in one go when it is safe and legal.

So, the correct behavior is to safely and confidently complete overtaking all the relevant vehicles (in this case, the blue car) and only then move into the middle lane. This keeps traffic flowing smoothly and prevents dangerous situations. Always prioritize safety and follow the "drive right" rule after overtaking.