Your question is System Design: Reddit-Style Site. 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 site like Reddit. Focus on the ML system for the home feed, including candidate generation, ranking, re-ranking, and feedback loops. Assume the product serves millions of users and must handle fresh posts, comments, and votes with low latency.