Because you went from a https site to a non secure one (http://sbjs.rocks) so the referer header was hidden.

See: https://en.wikipedia.org/wiki/HTTP_referer#Referer_hiding

I did the same but it worked for me (said hn), why didn't it work for the parent but it did for me?

Same for me and I’m curious why (Safari on iPhone)

I believe it's due to HN including this:

  <meta name="referrer" content="origin">

Not in the latest Chrome (Windows). Right-click, open in new window:

> Your source is news.ycombinator.com

Though it is noted in the usage:

> When a visitor come from https web-site to http, a request doesn’t have a referer.