Currently, the protocol of the URL in the Request object is set solely based on whether the incoming connection uses TLS:

However, in setups with a reverse proxy, it is necessary to take into account the protocol information from the Forwarded/X-Forwarded-For headers to get the protocol used by the original client.

This should most definitely be opt-in using a createRequestListener option as it allows for protocol spoofing in setups without a reverse proxy. Cf. for example Express's trust proxy option: https://expressjs.com/en/guide/behind-proxies.html

The existing createRequestListener option to set a fixed protocol is not sufficient for all setups, as clients might use different protocols and that information might be relevant for the application.

Last but not least: Thank you all for your great work on React Router and Remix!