You haven't been redirected. The redirection happens inside the server, it's never communicated to the client. Well, almost inside the server. The server first

You haven't been redirected. The redirection happens inside the server, it's never communicated to the client. Well, almost inside the server. The server first does TLS processing, then this part, then that which the backend developers see as "the server". From a backend developer's perspective, this code runs in the zone between browser and server, where load balancers and such live. Operationally the code runs on in the same rack, probably on the same CPU, as the backend code.