What I've seen (that doesn't outwardly appear astroturfed) is largely people getting their feelings hurt because of an opinion they've expressed about the qualities of project they're involved in, or just a user/fan of. Their dislike of the Linux kernel or the relative insecurity of desktop Linux projects in general tends to piss people off, even though the negative points they make are invariably detailed and well communicated.
Because of that, instead of refuting the actual argument being made, discussion always swings towards their tone.
What it is, exactly, that is objectionable? Are there personal attacks being made? Yeah. Towards the GrapheneOS developers. It's something I've seen for myself and if you get into these threads on HN early, you can see how the comment deletions pile up. When they say they are the target of organized disinfo and targeted attacks by malignant third parties, it's pretty easy to believe them. It is in the best interests of many, many very powerful people that GrapheneOS is destroyed.
No one who takes infosec seriously cares about GOS' PR filling their communication with tummy rubs and head pats. Infosec is a nightmare, adversaries are everywhere, all anyone should want to know is whatever is as close to the truth as possible.