I personally feel that company is conducting fake interviews routinely only to seek free design advise since the engineering leadership had real experience when handed over their jobs especially on Cloud Area. They want to know other company trade secrets and they want to interview you and most questions will be related to what they want to solve and how will you solve. There are complex problem that cannot be solved by existing team or need an architect overview on how to do. They will interview and ask the questions related to it. Please carefully on sharing the design details and resolution for the complex problems.