Elon Musk and Substack are beefing. Here's a rundown of the back and forth between the Twitter CEO and the blogging site.

• Twitter users began noticing Substack links were being suppressed beginning Thursday evening.
• Musk denied the links were "blocked" but said he believed that Substack was "unsafe."

Over the past few days, a war between subscription-based blogging website Substack and microblogging platform Twitter has been brewing — with the CEOs of both platforms publicly responding to the controversy.

Following the news that Twitter began suppressing links to Substack on its platform, CEO Chris Best responded to Twitter owner Elon Musk calling the situation "very frustrating" and denounced some of the claims that Musk made about the company.

One of these claims is that Substack was trying to "download a massive portion of the Twitter database," Musk wrote on Twitter Saturday, to help support its recently announced Twitter competitor, Substack Notes.

Twitter previously suppressed links in December to competing social media platform Mastodon.

As of Saturday evening, the warning labels had disappeared, but searches were still being redirected, Insider found.

"We're glad to see that the suppression of Substack publications on Twitter appears to be over," Best and Substack co-founders Hamish McKenzie and Jairaj Sethi said in a joint statement to Insider. "This is the right move for writers, who deserve the freedom to share their work. We believe that Twitter and Substack can continue to coexist and complement each other.

"We look forward to making Substack Notes available soon, but we expect it to be a new kind of place within a subscription network, not a replacement for existing social networks."

Here's a rundown of the back-and-forth that led to Best's latest response.

Wednesday: Substack announces Notes

On Wednesday, Substack announced in a blog post it would be rolling out a new feature called Notes, similarly styled to Twitter. Notes would allow users to post "short-form content and share ideas" that could be liked and commented on, similar to Twitter. Also like Twitter, these posts would show up in a scrolling feed.

"While Notes may look like familiar social media feeds, the key difference is in what you don't see. The Substack network runs on paid subscriptions, not ads. This changes everything," Substack wrote in the blog post.

It was not immediately clear if the announcement and Twitter's war against Substack links are related to the release of Notes.

Thursday evening: Users begin reporting that Substack links are being suppressed

Substack bloggers who use Twitter to promote their work began noticing Thursday evening the Substack links seemed to be suppressed on Twitter, and Twitter users who tried to interact with posts that contained Substack links would receive an error message.

Twitter also began redirecting searches for Substack to newsletters and if anyone clicked on a Substack link, they would receive a page warning them that the link was unsafe, Insider previously observed.

Substack also noted that writers on their site were having issues trying to embed Tweets into their blog posts.

In a statement to the Verge on Friday, Best said Substack was "disappointed" in the changes.

"This abrupt change is a reminder of why writers deserve a model that puts them in charge, that rewards great work with money, and that protects the free press and free speech," Best said in the statement to the Verge. "Their livelihoods should not be tied to platforms where they don't own their relationship with their audience, and where the rules can change on a whim."

Friday: One of Musk's 'Twitter Files' journalists says he's leaving

Matt Taibbi, a Substack blogger close to Musk who helped publicize some of Twitter's internal content moderation decisions through the "Twitter Files," wrote on his Substack blog that he would use the Substack Notes feature rather than Twitter to share his work.

Taibbi, who has tens of thousands of paid subscribers and charges $5 a month to access his content, also said the move would affect future "Twitter Files" reports.

Taibbi specifically cited Twitter's decision to "block" Substack links on the platform and said he asked "what was going on" and was told to post articles on Twitter instead. Taibbi did not clarify who he had spoken to.

A bot that tracks the Twitter accounts of Big Tech CEOs announced that Musk unfollowed Taibbi soon after. Insider confirmed this.

On Saturday evening, Journalist Matt Binder noted that Taibbi's tweets were no longer searchable on Twitter.

Taibbi did not immediately respond to Insider's request for comment.

In a statement to the New York Post on Saturday, Taibbi said that he appears to be caught in a "business dispute."

Saturday: Musk clarifies that Twitter never blocked Twitter notes

Musk clarified in a tweet early Saturday that Substack links were never blocked on Twitter.

However, Twitter users were quick to point out on Twitter's Community Notes — a feature that allows contributors to add context to posts —that Twitter did prohibit users from interacting with Tweets that contained Substack links.

In the same post, Musk called Substack Notes a "Twitter clone" and claimed that Substack was "trying to download a massive portion of the Twitter database to bootstrap" their new feature.

He also claimed that Taibbi worked or still works as an employee for Substack. Best denied this.

Substack's CEO says 'none' of Musk's claims are true

In a Notes post retrieved by the Verge, Best responded to Musk's tweets, saying "none of this is true."

"Substack links have been obviously severely throttled on Twitter. Anyone using the product can see this," Best wrote, in response to Musk's assertion that links to Substack were never blocked on the platform.

Best also replied, saying that although Substack uses Twitter's API to support the platform and they believed they were in compliance with the API's terms of use, but would be "happy" to address any concerns from Musk.

Best also denied that Taibbi had been or is an employee at Substack.

"This is very frustrating. It's one thing to mess with Substack, but quite another to treat writers this way," Best wrote.

A press email for Twitter automatically replied with a poop emoji.