Mashable: It's an Elon Musk decision in what should be CEO Linda Yaccarino's domain.

Are you still advertising on X, the Elon Musk-owned social media platform formerly known as Twitter? If so, you might have received an email about the company sunsetting one of its oldest advertising features: Promoted Accounts.

As first reported by Axios on Tuesday, X's advertising clients were informed via email that the Promoted Accounts feature, also known as "Follower Objective" ads, is being shut down. These ads are text-based content that appears in the timeline feed with a Follow button — they don't directly promote any content, the call-to-action is to simply follow the user.

This move from X is baffling when you consider that the ad format routinely generated more than $100 million per year in revenue for the platform, according to an Axios source who is familiar with X's business. The report mentions that these types of ads were "easy to sell," but didn't factor into the platform's plans for the future. With media such as videos being a focus for Musk, static-type ads like Promoted Accounts are being phased out. As of publishing time, advertisers can still run these ad types.

For users, the loss of these ads probably won't mean much. From personal experience as a power user of the platform, Promoted Accounts rarely matched my interests and often came off as spammy. However, they clearly seemed to be working for the company and at least some of its advertisers.

However, the more interesting tidbit here is how the decision was made to remove an ad format that was creating hundreds of millions of dollars in revenue for the company. According to Axios' source, "the change was driven by X's product group, not the revenue side of the company." Emphasis added.

This is notable, as it continues to show that Elon Musk is in charge here. Of course, this seems obvious, as it is his company. However, Musk specifically brought on Linda Yaccarino to be CEO of X. And, her actual role within X has routinely come up for debate, like when Musk announced Twitter was rebranding as X and the company's CEO took nearly 17 hours to even put out a statement or make a comment of her own.

In her recent interview with CNBC, Yaccarino made it clear that her role was to run the "business" side of the company while Musk took care of the tech product end of things. Yaccarino's entire area of expertise is in the advertising industry. Yet, according to Axios' source, Musk and his product team were the ones who made this very specific decision for a revenue-generating advertising aspect of the company.

The removal of Promoted Accounts isn't the first big ad decision made by the company in recent months. The platform has rolled out new ad features for brands in hopes of revitalizing its ad revenue, which took a nosedive after Musk acquired the company. Last week, X rolled out a "sensitivity settings" tool to give advertisers more control over what type of content their ads would appear next to. And, as first noticed last month, X seems to still be experimenting with its ad labeling formats, which show users exactly what content is a paid ad.