My recollection - and I don't play Germany so I may be wrong - is that there was some kind of funky reorganization of the two lowest playable German leagues this season, which led to a one-off promotion/relegation structure for the first season which differed from what the rules stated.
I believe the rules and behavior match for the second season.
Clever use of "Find" should be able to come up with threads on this issue in the September-November time frame, but I didn't spot it on my first two tries.