For each request, the address https://d9iphvhnmgdn1.cloudfront.net/{version number}/index.html is called — this retrieves the version corresponding to the currently installed server version. Directory listing is disabled on S3. As mentioned, this is always downloaded with every request.
It then downloads the index.html file from https://d9iphvhnmgdn1.cloudfront.net/versions.json, replaces the resource loading paths within it (other JS files, etc.) with the correct paths, and returns the information as the server response to the call on localhost:5434 (or any other address configured within the network).
Subsequently, the browser itself calls the resource paths directly, rather than the server itself.
The two URLs mentioned above must always be accessible for the web interface to function. Without ensuring this, it cannot operate.