I definitely failed at one or two places on the behavioral / experience questions, but a few told me explicitly I need to improve my technical chops (I was grateful for the feedback). I felt like nobody was unfair at all, and that I just need to refresh my knowledge in the fundamentals. Basic DS & algos, concurrency, programming language trivia, etc.

Startups are kind of hard to get an interview at these days, you ideally should know someone already working in one, who can vouch for you. I don't feel like they have a low bar either, just less rounds.