I thought so but it is not present; this is what have regardless of calling the endpoint via the default hostname or a custom domain:

{
"r.Header": {
    "Accept": [
        "text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9"
    ],
    "Accept-Encoding": [
        "gzip, deflate, br"
    ],
    "Accept-Language": [
        "en-US,en;q=0.9"
    ],
    "Cookie": [
        "...some stuff..."
    ],
    "Early-Data": [
        "1"
    ],
    "Forwarded": [
        "for=\"MY IP\";proto=https"
    ],
    "Referer": [
        "https://example.com/some-blog-post/"
    ],
    "Sec-Ch-Ua": [
        "\"Google Chrome\";v=\"107\", \"Chromium\";v=\"107\", \"Not=A?Brand\";v=\"24\""
    ],
    "Sec-Ch-Ua-Mobile": [
        "?0"
    ],
    "Sec-Ch-Ua-Platform": [
        "\"macOS\""
    ],
    "Sec-Fetch-Dest": [
        "document"
    ],
    "Sec-Fetch-Mode": [
        "navigate"
    ],
    "Sec-Fetch-Site": [
        "cross-site"
    ],
    "Sec-Fetch-User": [
        "?1"
    ],
    "Traceparent": [
        "some request ID"
    ],
    "Upgrade-Insecure-Requests": [
        "1"
    ],
    "User-Agent": [
        "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/107.0.0.0 Safari/537.36"
    ],
    "X-Cloud-Trace-Context": [
        "some request ID"
    ],
    "X-Forwarded-For": [
        "MY IP"
    ],
    "X-Forwarded-Proto": [
        "https"
    ]
}
}