Expedia Group interview questions

I was reached out by a recruiter and asked if interested. When I was positive about moving forward, he sent me a coding challenge which was quiet difficult (it included DP problems). I scored quiet well in the challenge so was called in for an in-person interview. Expedia flew me to their Seattle office. There I had 4 interview rounds. In 2 rounds they went over my resume points and asked me to provide approaches based on technologies I mentioned in my resume. Other 2 rounds started with initial talk about me followed by coding question (white board), these were way too simple as compared to coding challenge. The interviewers were very supportive throughout the interview and very helpful at places I got stuck. I received an email next day to interview from recruiter that I have been rejected, when asked for the reason, the recruiter said due to company policy he can not give those details. It was a good experience except the rejection as I was confident that I performed well.