Started with OA, a bit hard was only able to solve 1 but still got call for interview.
All rounds happened within same week and virtual interview were on Chime. Each round had 2-3 leadership-based question.

• Round 1: Hiring manager: Discussion about the project and LLD for a DNS resolver with a health check. Follow-up: support TTL and fast on reads.
• Round 2: System design for Twitter: Consistent tweet write with HA, followers list, timeline, and consistent tweet ID support. Follow up: support 5MB video with tweet. Topics: NoSql vs SQL, Fast write DB (LSM tree vs BTree, cassandra internal), Consistent Hashing (tweet id generation), read-after-write consistency, geo load balancer, Sharding (Partition) vs Replication, Skewed partition issue (celebrity issue).
• Round 3: DSA:
  a) https://leetcode.com/problems/find-median-from-data-stream/description/
  b) https://leetcode.com/problems/first-missing-positive/description/
  I was able to solve (a) with most optimal approach and (b) with TC: O(n) and SC: O(n). Space complexiy expected was O(1).
• Round 4: LLD: "Design an event forwarding framework where event generated from a system(s) is required to be consumed by another system(s)."
  So, question was like event producer and consumer, with batch processing and some event processing can take lot of time, events can fail and shouldn't block other events.

After 2 week got rejection email.

Thanks and hope this post helps!