The former. Brave has explained their referer policy here: https://brave.com/privacy-updates-5/

> When navigating to a new site, never send a referer header.

JWZ wouldn't know you are visiting from HN if you use Brave.

Also, if you're using a Hacker News app, it won't send a Referer header when opening an article unless the app authors went out of their way to implement that. I would be surprised if any did.