X-forwarded-host header seems wrong for requests using an http integration proxy

I'm using curl to make a request from one VM to another, using an http integration proxy. I expected the "x-forwarded-host" header to be the hostname that I passed to curl, ending in "int.exe.xyz". But actually, it's the regular https hostname without "int", as would happen if I connected to the VM from my web browser.

I'm not sure what's supposed to happen, but it seems confusing to have requests coming in from the outside and internal requests going through the proxy to have the same hostname.

Workaround: set a bearer token in the http proxy. This is less convenient because the bearer token is a secret that the server needs to protect against leaks.