That is true here too. And Twitter is the least transparent, with people regularly reporting that posts critical of musk or trump have reduced reach compared to their other posts.
Ah, no, the HN commentorship is quite highly biased toward a particular demographic and set of political beliefs, which is a thing that needs to be acknowledged. "Considering both sides" is not something I've ever seen as common practice in any organic online community I've been a part of, full stop.
HN's redeeming quality over much of the rest of the web is that low-effort hot-takes and aggressive content are actively discouraged by the mods and community. (These are things that other communities devolve towards, because they tend to drive engagement faster and easier than quality.)
I don't know whether this is true, but I've seen exactly the same "complaint" from both sides of the USA political spectrum (USA politics are overrepresented for obvious reasons).