Is there a place to flag shill accounts?

I've noticed a trio of shill accounts posting links to an external newsletter service. All three accounts seem to date from about the same time this year. All have a similar number of comments and follow a similar pattern: every third or so comment contains a link to the newsletter site. Their bios are very different, and drawn from stereotypes of their target subscribers. I'm pretty sure they're all sock-puppets of a Marketplace contributor account.

Hate to be another Karen, I should just mute them and move on, but this spam detracts from SA's reputation and utility. It's particularly troubling when a Marketplace contributor is involved. Is there some way of reporting shill accounts so SA can investigate further?