What can you expect now?

You chose both “brake” and “stay in the middle lane,” which is correct. On a German Autobahn, if you are overtaking slower vehicles in the right lane and there is another vehicle ahead of you in the left (overtaking) lane, you must be prepared to brake if necessary to maintain a safe distance and avoid getting too close. At the same time, you should stay in your lane while overtaking and only return to the right lane when you have safely passed all the slower vehicles and it is clear. Accelerating is not the right choice here because your speed should be adapted to the traffic conditions and the safe distance to the car in front. In summary, the best actions are remaining in your lane and being ready to brake if the vehicle in front slows down. This follows the rules for safe overtaking and lane use on the Autobahn.