The app is rarely alone. A proxy, a load balancer, and a CDN sit in front of it, and each one rewrites a header the app wrote.
About 1 min of reading
Order the timeouts
Write the layer timeouts
Before you run it, say out loud what it will print. Then open the answer.
Write the order rule
Before you run it, say out loud what it will print. Then open the answer.
Name the forwarded header
Before you run it, say out loud what it will print. Then open the answer.
The drawing names each layer and its timeout. A drawing with numbers is a drawing that can be argued with.
A behaviour that works in a test and fails in place. The difference is a layer, and the layer is the cause.
The proxy ends TLS and the app sees http. A redirect built from the app view is a redirect to the wrong host.
The proxy says what it removed. The app reads the claim, and the claim is a header both sides must agree on.
Each layer has its own timeout. The smallest timeout is the ceiling, and the ceiling is not the app's.
Each one is defined here on this site. Open the entry for the full definition and the other words it points at.