Two of the three coding rounds (including the first) were problems you might see on the job, one of those with an OO focus that also touched on multithreading. The other was a DSA focus with a medium-level Leetcode problem. Kudos to them for asking some real-world problems and not just LC. For coding prep I would focus on being able to write quality code fairly quickly. None of the problems required a lot of code but you want to write it like it's production code. The OO question in particular had a lot packed into it and the time sort of got away from me. I don't recommend using a verbose language like Java or C++ unless that's all you know well (I used Python). For the system design round, was asked to design a specific feature in a well known app. The interviewer scoped the problem at a small/medium scale and did not ask about scaling up, and I got feedback that they wanted to see a design that scaled better. I think this is ultimately what sunk me. So I recommend designing or at least talking about scale unprompted.