Round 1: Low level OOPS Design: Design in-memory SQL(Questions like write function to add, remove the table, select * from table, delete from a table, etc). Time is less for writing full working code, so explained the pseudocode only(But I think the interviewer expects to write partial working code).
Round 2: Design Notification System(High-level design). The design should include all notifications like Push Notifications, SMS, Webhooks, Email, etc. Also, identify bottlenecks & how would you solve them.
Round 3: Hiring Manager Round.Many questions like any argument with seniors, projects, design patterns that could be implemented in your project, why so many switches.
Verdict: Got rejected as SDE-2 and both, the company and me thought will not fit in the SDE-1 role
Tips: You should be great at design interview questions, maybe require maturity of 5+ years.