Your question is WAU/MAU Table Design. Take a moment with it on the right.
Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).
Design a table (name the columns) to calculate WAU (weekly active users) and MAU (monthly active users), such that the table doesn't break and the calculation stays fast
Asked in the hiring manager round stage. Round 3. Explain the table grain, column choices, uniqueness strategy, period definitions, and how queries would avoid duplicate users while remaining efficient at scale.