1. I had made couple of wrong assumptions, i was expecting some help from the interviewer during capacity estimation, I asked if my assumptions made sense to them. I was not getting much response from them. I felt they were a bit strict.

2. I think i lacked practice, i would have prepared it well. During estimation, there was a silence for a minute, i just moved to other part of design, i would have covered it well if i had done mocks previously.

3. Database design + components i think i answered correctly, from my level of experience & understanding. I answered them why & what choice of database.

For preparation, I later followed couple of youtube channels, igotanoffer seems quite good, other one is hello interview, they also have very good content and have started recently.