It's still there.

    $ curl -D - -H 'referer:https://news.ycombinator.com' 'https://www.jwz.org/blog/2021/06/to-be-clear-the-whale-did-not-want-him-in-its-mouth/'

    HTTP/1.1 302 Found
    ...
    Location: https://cdn.jwz.org/images/2016/hn.png

Your browser probably isn't sending the referer for third-party sites. (I've configured mine to not do that as well.)