Gremlin Software Engineer interview questions

Echoing previous submissions here - the interview process had a lot of red flags and they were very unorganized throughout, almost to the point where they were wasting my time. The interview process started off very typical - a phone screen, initial behavioral interview, then a take-home code challenge that involved creating an app from scratch, with responsive design, business logic, and unit testing. I submitted my assignment then heard no response for a week and a half, even after a follow-up email. Finally, I got advanced to the next step that was going to be a multi-round behavioral/technical interview with four different people. At the last minute, the recruiting coordinator told me I was going to be interviewing with just one person because they were restructuring their interview process. The interview was with a backend developer. Nothing was mentioned of my homework assignment nor was it a really technical interview because he was a backend engineer interviewing me as a frontend. It felt like they just threw this guy at me even though it didn't make much sense for him to be interviewing me. The interview went well, despite that, and I was given an invite to a final round with higher-ups execs. Then, 30 minutes before the interview, I got a rejection letter and the meeting was cancelled, with no explanation why even after following up. So to sum up, there was a complete lack of communication and I felt like I was being strung along.