BNP Paribas Data Scientist interview questions

Applied through their official website. A recruiter contacted me and scheduled the interview. To my surprise, the interviewer turned out to be the Head of the department I had applied to. Unfortunately, I didn't perform well and felt like I came across as unprepared. At the end of the interview, I asked a simple question: "What's the most difficult or interesting problem you've worked on at BNP?" His response was, "I don't think any of the problems are big or tough for me." After saying that, he abruptly ended the call.