HTTP/3: allowed QUIC stream connection reuse. A QUIC stream connection is treated as reusable until first bytes of request arrive, which is also when the request object is now allocated. A connection closed as a result of draining, is reset with the error code H3_REQUEST_REJECTED. Such behavior is allowed by quic-http-34: Once a request stream has been opened, the request MAY be cancelled by either endpoint. Clients cancel requests if the response is no longer of interest; servers cancel requests if they are unable to or choose not to respond. When the server cancels a request without performing any application processing, the request is considered "rejected." The server SHOULD abort its response stream with the error code H3_REQUEST_REJECTED. The client can treat requests rejected by the server as though they had never been sent at all, thereby allowing them to be retried later.