That's not uncommon. The easiest explanation is the simplest: randomness.

is there a HN discord or something?

There's a semi-secret, invite-only, HN Slack channel.

[Edit: I don't think I mean channel but the terminology for what I'm saying eludes me]

...so how do I get an invite?

Is it possible to get an invite?

It wouldn't surprise me, even if it were not officially sanctioned. Perhaps this is just the human desire to find patterns in everything, but I have seen at least some evidence of coordinated up/downvoting that pushes specific agendas on here. The unending GDPR fanboyism is one example. It's either the worst case of groupthink I have ever seen, or people are coordinating.

It's no secret that many people on Hacker News would like stronger privacy regulation.

I don't want to get into a long GDPR discussion, but the idea of privacy regulation is great. GDPR, however, is deeply flawed. Yet any comment even attempting to discuss those flaws in a rational manner are instantly downvoted into oblivion, while comments glossing over its flaws are instantly upvoted. It's pretty clear that there is some coordination going on.

Not trying to be snarky, but my experience is almost exactly the opposite.

I can't comment on voting patterns, but while GDPR was being prepared, and after it was released, there was an endless barrage of posts claiming how it was flawed, lead to the ruin of technology companies in Europe etc, and it should be replaced by something else (anything else, at some point in the future - and in the meanwhile please stop getting in the way of tech companies trying to make a profit)

Frankly I would not be surprised if there was indeed a reflexive downvote effect that is not caused by a shady conspiracy but rather people like me who are tired of posts like that.