Phone call with recruiter. Then 1-hour video call with a team member. Then a 4-5 hour virtual onsite.

I got the impression that the work culture was questionable. To be fair, most of the interviewers were professional, but one in particular was unprofessional.

For example, during one of the onsite rounds, the interviewer repeatedly complained about turnover on his team. Specifically, he kept complaining about someone who had left his team after just one year. He repeatedly brought up this person throughout the interview and said he had left due to his unwillingness to learn. It is unprofessional to talk about your staff to others, and more unprofessional to complain about your staff to candidates. This was one of the many red flags, and I do not blame this person for leaving. I highly doubt he left because he was unwilling to learn.

I strongly considered simply walking out partway. I felt it would be unprofessional as I had already committed to the rest of the rounds that day. However, in retrospect, I should have done this, as it was a waste of time.

Very easy and straightforward string question.