> comments are filled with random LLM bots

Let's say you're right. What good is going to come from posting a comment calling attention to that? As far as I can tell, that's just more noise masking whatever signal is present in the conversation.

The guidelines also say:

Please don't post insinuations about astroturfing, shilling, brigading, foreign agents, and the like. It degrades discussion and is usually mistaken. If you're worried about abuse, email hn@ycombinator.com and we'll look at the data.

I would think "accusations of comments being authored by an LLM" would fall into this regime. Probably better to just email the mods, than posting a comment that nobody wants to read, and which is not guaranteed to be seen or acted on by the mods.

I would say no. Criticize the posts or downvote/flag them or email the moderators with your concerns. Generalized comments about declining comment quality on HN is pointless and just adds to the noise that users have to slog through.