Overall, it was a good experience. There was one interviewer who acted standoff-ish and strange. But, for the most part, it was conducted very professionally.
What I didn't like was the Systems interview question, which is a very specific modelling problem and unless you've worked on building such a feature, it's unlikely that you'll recognize such a pattern and come up with a decent solution. And for a mid-level position, it's quite surprising. But I guess they gotta justify the high comps somehow. Also, infrastructure knowledge is not tested at all in this interview, which is atypical.
The coding interviews were great. Study typical LLD problems. Leetcode is minimal and simple. Focus on understanding patterns and not memorizing solutions.
The HM interview was great. He probed in ways typical EMs have never done before, and it gave me a really good impression of the company and his team, despite also not passing this interview, which I take full responsibility for.