I can confirm I've personally been asked to post things on HN because I have an old account and so it would look more organic (I did not, not saying who asked because I'm not interested in starting a brouhaha).

my account is a year older than yours and I've never been asked by shadowy interest groups to astroturf, do you have any tips to improve my account's brand appeal?

Probably a combination of chance, ease of contact, and working for a large tech company thus signaling general obedience. It's not like it happens all the time, only happened once.

I presume you notified DanG. What did he say/do?

I wouldn't say well known, but it is reasonable to assume that some entities would have interest in swaying the HN community enough to put some effort into it. Yesterday for example the thread "Show HN: Twingate – A modern solution for remote access"[1] showed some signs of astroturfing as pointed out in the comment by crmrc114. Possibly as a form of advertising.

Response was very quick as I have usually seen though.

[1]: https://news.ycombinator.com/item?id=23326755