This week, Twitter began restricting the promotion of links to Substack newsletters, a move that seems to fly in the face of owner Elon Musk’s vocal support of free speech on the platform. The change is a huge problem for Substack writers, who have found Twitter to be one of the best places to attract new subscribers to their newsletters.

“It appears that Musk is making decisions based on his own financial interests and petty grievances — even if it makes Twitter objectively worse for users,” Judd Legum, author of Popular Information, a politics-focused newsletter with more than 240,000 subscribers, says in an email to The Verge. “If this continues, it’s hard to justify continuing to invest my time creating content on Twitter.”

The ban on Substack promotion, which was enacted between Thursday night and Friday morning, makes things difficult for many Substackers who use Twitter to promote their newsletters. If a new tweet links to any page on “substack.com,” users can’t like, reply to, or retweet it. While some Substack writers have custom domains, which skirts the ban, the policy change impacts the vast majority of newsletters on the platform, including some of its top names.

That severely limits the ability for newsletters to spread on Twitter. Right now, an author tweeting a substack.com URL won’t get any engagement on their own tweets, for example. If somebody wants to share an interesting substack.com link to their followers, those followers can’t easily share or reply to that tweet. That can lead to fewer people finding the newsletter and its author, which can hurt their ability to grow a business around it.

“Given my massive Twitter following, I heavily rely on tweets to convert new subscribers,” says Matt Swider, author of The Shortcut. “My goal is to reach people on their platform of choice, so when platforms are at war like this, it only hurts the creators.”

Substack author Laura Jedeed tells The Verge she got her biggest subscription spikes based on tweets that did “very well.” Jedeed also says she sees subscription bumps “every time Musk does something stupid” because “I think people realize Twitter is dying and they want to keep hearing from me after it falls apart,” she says. “He’s driving traffic my way by being stupid but, like everything he does, it’s killing the goose that lays the golden egg.”

Twitter and Musk have yet to acknowledge the ban. Twitter previously ran its own paid newsletter business, but Musk shut it down.

The block on Substack links is notable enough that Matt Taibbi, who Twitter worked with directly for multiple “The Twitter Files” disclosures, said Friday that he planned to move from Twitter to Substack’s Notes.

Others have said they may dump Twitter, too. Laura Jedeed is threatening to leave Twitter if the Substack restrictions aren’t reversed in a week. Erik Hoel, author of The Intrinsic Perspective, says he canceled his Twitter Blue subscription and “likely won’t be on this godforsaken platform for much longer.” Eric Newcomer of the Newcomer newsletter is encouraging people to sign up for his newsletter and watch for his Substack Notes, a new Twitter-like feature Substack just announced on Wednesday.

Twitter’s choice to restrict the sharing of Substack links shortly after that Notes announcement makes the decision seem like a direct response — and Taibbi claims that’s indeed the case.

Substack founders Jairaj Sethi, Chris Best, and Hamish McKenzie criticized Twitter’s move, calling it a “reminder of why cracks are starting to show in the internet’s legacy business models.” The company adds that it hopes to “ensure that writers and creators get only more ownership and control of their futures.”

Since announcing his plans to acquire Twitter, Musk has spoken at length about the importance of free speech on Twitter while reiterating his vision of making the platform a “digital town square.” Last year, Musk established a policy that would allow “freedom of speech, but not freedom of reach,” indicating Twitter will make negative tweets less visible but will generally strive to allow content to be posted to the platform.

However, the new limitations imposed on Substack links have users questioning Musk’s commitment to free speech — especially since this isn’t the only incident that has prevented people from posting links to other platforms. Last December, Musk started banning journalists critical of him and abruptly banned links to Facebook, Instagram, Mastodon, Truth Social, and other competing platforms. Musk rolled back those changes, stating major policy adjustments would be put to a vote from then on, which they haven’t.

“Substack is a vital platform for independent journalism and for providing quality alternatives to corporate media, and it would be both unfortunate and contrary to the stated free speech goals of Twitter’s current management to ban both Substack writers and readers from using Twitter to promote Substack articles,” journalist Glenn Greenwald said in an email to The Verge. Greenwald published on Substack until this year; he now writes on Rumble’s Locals platform.

That said, it appears that some bigger Substackers are in a position where they can safely move away from Twitter anyway. Legum tells The Verge that while Twitter used to be a “major source” of new subscribers, Substack’s recommendations network now drives “about 3-4x more” than Twitter. Substack introduced its recommendations feature last in April 2022, noting that “writers cross-promoting each other has been the key to discovery on the internet since its inception.”

Newcomer already has more subscribers on Substack (more than 58,000) than followers on Twitter (~37,800), so he believes he’ll be safe. Even though that’s the case, he’s still unhappy with how things are going. “When you’re an independent creator, every platform matters,” Newcomer says. “So it’s extremely disappointing that Elon Musk has talked such a big game about supporting independent voices and then seems to be cutting them off at the knees.”