I can provide some hypotheses based on experience: Comments that support certain political positions are consistently downvoted. IME it happens with comments that are,

- critical of the Chinese government

- discuss Russian propaganda and trolling/astroturfing (other than to deny their existence)

- critical or questioning of the white male supremacist movement (alt-right) principles, in their propagandized 'reasonable' forms - though those comments are regularly voted back up by others; I've seen some wild fluctuations.

- critical or questioning of Elon Musk

I'm sure there are other topics that I'm not remembering. I guessed that the GP comment would be downvoted when I posted it.

Note that the first two subjects in my list have massive, well-documented online astroturfing and propaganda operations, and the third is no slouch in that area. HN policy, in kind of an odd political correctness, protects those people by forbidding any suggestion that such things are occurring - even as a possibility to consider. Don't mention the Emperor's clothes. That must make it heaven for astroturfers, propagandists, and naked Emperors everywhere.

Musk's fanboys are extreme: Drink the kool-ade or die. The man himself seems obsessed with image but enough to run an astroturfing operation? I have no knowledge that he does but would it be a surprise? Certainly he's not in the category with the other three for many very obvious reasons. For example, I hope he isn't in the dustbin of history but succeeds wildly.

Finally, the first sentence of my comment didn't help; it's a bit sharp, but that imperfection shouldn't be a big deal.

EDIT: I also wonder why alphaalpha101's comment is dead. It's not brilliant, IMHO, but certainly sufficient.