The recruiter will call you just to make sure you are prepared for the actual interview with the team manager and to answer any questions you may have. They won't tell you who is interviewing you prior to the interview, though, for privacy reasons apparently. The first round was mainly data structures, and the second round covered operating systems and a LeetCode question.

Questions were asked about the structure of a linked list and the structure of a hash table.

Space and time complexity questions were posed.

How to remove duplicates from a list and how to optimize solutions were also discussed.