Meta recently introduced its Muse app for Mac users, offering a Muse AI agent that performs tasks on users' behalf, including booking travel, browsing the web, and negotiating. Former X Head of Product Nikita Bier, who continues to advise Elon Musk's X, took a dig at Meta CEO Mark Zuckerberg, saying the negotiation feature could particularly hurt Facebook Marketplace. In his X post, Bier said one of Muse's launch features was auto-negotiating for products on Facebook Marketplace, which he believes may create a problem for sellers. He said, "The poor product manager who owns Marketplace knows that millions of bots lowballing sellers will eventually kill the product. But this was escalated to Zuck by the Muse team and he said: 'OK, we'll poison Marketplace…but just a little.'" Meta introduced Muse as a personal AI agent earlier this month, designed to take action on a user's behalf rather than mainly answer questions. It runs on a dedicated virtual machine called Muse Secure VM and can send emails, book travel, open a browser, and fill out forms. Bier's criticism suggests that if large numbers of AI agents start negotiating automatically, sellers could receive many low offers without knowing whether they are dealing with a human or a bot.