The process as a whole felt very unprofessional - lots of last second changes and some interviewers were not equipped for the role.
While the problems asked were not abnormally difficult, the interviewers were very intent on solving the problem "their way", even if your solution was the same complexity or better. It was hard to go through the standard problem solving process when the interviewer would constantly interject and nudge you in the way they wanted to go (despite the overall solution remaining the same). This is not how things work in a day-to-day engineering role. I was able to solve every question asked of me within the time given, but I think the interviewers believed I "needed help" because I was not given the opportunity to apply my problem solving abilities.
The system design portion was the worst by far - I was told "there are physical devices in the field with a central hub", and that's it. I tried asking clarifying questions ("what is even the problem statement here?", "what are we trying to implement?"), but it seemed like they wanted me to make up the scenario myself. This was way beyond just "clarifying vague requirements".
The behavioral interview was odd - they wanted to go through each of my job experiences one by one with a cookie cutter questions template. The interviewer was nice and professional though, and this was probably the most informative part of my interview.