I also suppose that this may be the default for a particular audience / geolocation. That is, maybe they'd show a different thing in Russia (sorry, I don't have a Russian VPN), and maybe even a different thing in Texas. Or maybe something based on your previous browsing history (e.g. if you read something like zerohedge a lot, they might show you a different, more aligned site).
I don't know, and am not inclined to thoroughly experiment. But the complete source is there, and it must be a relatively recent addition, so anybody interested could just dive in and find out. Yay Mozilla!
Second, I don't believe the source code of the algorithm that picks which news to show you is available... If there's an algorithm at all, because chances are it's curated by humans.
My recommendations for this are the BBC RSS feed, PBS NewsHour for nightly news / video (Youtube or OTA antenna) and a local paper RSS feed (Chicago Tribune for me). Though that paper has long been considered politically biased (to the right), local events are probably more important than national or worldwide news coverage so one has to bite the bullet at a point.
BBC/Tribune/PBS are simply exceptional reporting, regardless of any leanings, and I'd put that ahead of worrying about a lack of total neutrality. It's a little overblown. It's been clear for some time now that there's a bit of a struggle for right-wingers on being able to mentally muster their way through biased reporting (real or perceived). There's a lot of weak and fragile people around today, can't even watch or read something that doesn't cater to their sensitivities. It used to be that a right-winger aspired to be John Wayne. Now they're all-in on victimhood culture. If they did anything in their life at all, like get off the couch to join the military (which is a government dependent of the worst kind- one that leads to people getting killed, rather than an unpaid, sacrificial service), they're deeply offended if you're not constantly kissing the ring.
Maybe checking just the AP releases would be the best way to get "neutral news", but I think if you just hunt for sources that explicitly do not sensationalize the news, something Fox News brought into popularity, you'll get most of the way there.