There were 6 interviews: 2 screenings, System Design, Product, Backend, and Algorithms (TF-IDF, yes). The first screening went really smoothly—the interviewer was polite and friendly. Starting from the second screening, I began noticing that the interviewers weren't very interested in the process. They would just give a task and listen silently (some even turned off their cameras, lol) until the end.
System Design: OK, the interviewer was really polite, descriptive, and dialogue-oriented. The only interview I can highlight positively.
Product interview: the worst interview I've ever had. This guy was asking me about analytics, some business questions, and how to increase ROI, ROAS, and other metrics with given inputs. Rather than displaying the formulas, he verbally explained them, which made things more difficult.
Backend interview: consisted of an algorithm task (what?) and a system design task (what? x2). Also, this interviewer was 10 minutes late, and I was about to leave. This guy also asked a lot about cryptography and security. This seemed REALLY strange because I had literally just completed the system design interview a few days earlier. What made it even stranger was that the algorithm interview was scheduled right after this one.
Algorithm interview: 2 guys watching you do some data engineering work (even though it's a fullstack position) for an hour, with their cameras and mics turned off. There's only you and silence, that's it.
I'm glad I was rejected because they're looking for a one-person orchestra who can do: business, analytics, data engineering, backend engineering, frontend engineering, probably account management, security engineering, and so on.