To summarize, it is a total waste of time.
The first round was a technical interview talking about a completed take home assignment and basic data analyses stuff. It was pretty easy.
The second round was with a senior guy of an irrelavant team who knows nothing about data science (quite surprising). The interviewer looked like being forced to be present in the interview. He showed no interest in my background and finished his question in 15min.
I think they do not know what kind of person they are looking for. The interviewers tried to be nice but I got wired feelings of talking to them for no reason. They are hiring because several people left the data science team. Given this interview experience, I do not wonder why people left.