Mastodon CEO Eugen Rochko has spoken out about the significant moderation changes announced by Meta on Tuesday, which will see the social networking giant removing fact-checking across its apps in favor of a crowdsourced community notes feature, similar to X’s. The Mastodon founder, whose app competes with X and Meta’s X rival, Instagram Threads, called Meta’s changes “deeply troubling” and “a concern to anyone with a conscience.” He also warned Threads users who cross-post from Threads to Mastodon via Threads’ fediverse-sharing feature that Mastodon will take action on hate speech and any Threads account violating Mastodon’s existing policies.

Following the announcement of Meta’s loosened content moderation rules, which affect LGBTQ communities and other marginalized users, many Mastodon users wanted to know what this meant for the open source, decentralized social network, given its connection with Threads.

Last June, Meta opened up its fediverse-sharing feature to all Threads users after earlier beta testing in the U.S., Canada, and Japan. The feature lets Threads’ users enable an option that will publish their posts directly on Mastodon as well, allowing them to reach a broader audience.

Rochko previously touted Threads’ federation, saying the move made the open source Mastodon a “far more attractive option.” He has also spoken about how Meta’s adoption of the underlying ActivityPub protocol, which powers Mastodon and other federated servers, was a validation of the move to decentralized social media.

However, not all in the fediverse are in universal agreement on Mastodon’s integration with Threads. Hundreds of smaller Mastodon servers block Threads, which means their users can’t connect with Threads users or vice versa. (Meta also blocks hundreds of Mastodon servers, too, over violations of Community Standards and other moderation and privacy issues.)

It was previously unclear how Mastodon would respond to Meta’s new policy, and whether or not the larger Mastodon instances, like mastodon.social, would now take action against Threads accounts.

Rochko’s post indicates the organization is aware that Threads integration could soon become a moderation challenge. “Hate speech is prohibited, and we will take action on any Threads account found violating our policies,” he warned in a post on his Mastodon account.

He also urged users on Threads who disagreed with Meta’s new direction to move to Mastodon instead, though it’s not as easy to do as moving an account between different Mastodon servers. That’s because Threads is not yet fully integrated with the fediverse in this way.