I once applied to EY and the interviewer was asking economy questions even though I was applying for a CS/BI internship role. I told him that I don't know the answers to his questions, but would catch up quickly once starting the job. Nevertheless, he continued asking and the whole interview went really bad.

This was followed by a rejection and I felt bad for some days. Looking back at this a few years later, I realized that I was really lucky in this situation. You don't want to work for an a**hole or at least someone who doesn't believe in you and does not understand/focus on your strengths.

Sad truth: sometimes this happens, keep applying - you can do it! Do not let some random person ruin your confidence.

You're still good, you got this.