Fast Paint, Dead Page
Decide what you would build from the brief alone. Everything below it is available, but the exercise stops working if you open it first.
A server-rendered marketing page paints its content quickly and then ignores clicks for a noticeable window. The loading measurement looks excellent. Explain and fix.
Adding a full-page loading overlay that is removed when hydration completes, so users cannot click a dead control. The mis-click complaints stop and the page now behaves consistently. It has also given up the entire benefit of server rendering — the user is looking at an overlay instead of the content that was already painted and ready to read — and the loading measurement that looked excellent gets worse, because the meaningful content is now covered. The correct move is to make the window shorter and the interactive affordances honest, not to hide the content that arrived on time.