In case of HTTP/2 and HTTP/3 the request does not need to contain host header.

In case of HTTP/2 if there is no host header, Nginx produces one (in r->headers_in structure, beside the r->headers_in.host and r->headers_in.server), so you you will get a host header if you iterate r->headers_in.headers structure.

But not in case of HTTP/3.

Is there any reason that v3 HTTP module does not do this?