Prelude interview questions

I had 4 rounds of interviews and I met with the CEO twice. Everyone was very friendly except for one person who seemed to be too busy to focus on the interview itself. My last interview involved 3 Hours of meeting many different people from the company (after completing a homework assignment) to see if I'd be a good culture fit. I got rejected the next day. I asked for feedback twice and never heard back. I had 4 rounds of interviews, met with the CEO twice, did the homework, and had a 3 Hour interview but somehow they feel that giving feedback is unecessary let alone reply to an email in general.

I applied for the position and the recruiter scheduled a screening I guess based on my resume. The recruiter scheduled the interview on google calendar and the call on zoom (Although according to the recruiter the company product is live and the product is supposed to be interview scheduling) It was the shortest interview preceded by two reminders. I am just irritated because of the time wasted, she simply could have emailed me those questions. And again they are building Prelude #1 InterviewScheduling