If you aced the technical questions, then it must be the behavioral part. One big trap there is the question about conflict resolution. The naive answer "I avoid conflicts" is a mistake: according to the trendy big five personality traits system, avoiding conflicts is a sign of guess what? combative personality. You want to present yourself as a "agreeable" person. The person asking these questions is rarely a psychologist. Instead the interviewer is given a big spreadsheet with 50 or so canned questions and 5 or so columns with examples of answers and how those answers must be interpreted. Finally the interviewer crosschecks your answers with the spreadsheet and gives ratings to five personality traits. In your case, you must be said some keyword, the interviewers, who can't care less, matched that keyword with the spreadsheet and you got a bad rating. The HRs also can't care less, so they obviously don't bother to double-check the ratings (if anyone bothered to actually record your answer). Anyways, morale of the story is that behavioral questions are just like leetcode: you need to know the right answers before you start the interview.