While Twitter users are watching Elon Musk start fires, put them out and start others, Mastodon is seeing a sizable uptick in its user base. Last Sunday, it said it gained 489,000 users in less than two weeks, giving it more than 1.5 million active monthly users.

Brands may also be looking for a new home. Chipotle, United Airlines, General Mills, Pfizer, Audi, Volkswagen, Ford and General Motors have all yanked ads from Twitter, Forbes reported on Thursday. Ad buyers are advising clients to pause Twitter spending, and given how many new eyes are on Mastodon, it may look like an appealing alternative. But before everyone jumps ship, here are five things for brands and marketers to know about Mastodon.

Individual servers break up the culture

When a user signs up for Mastodon, they choose which server they’d like to join based on their interests. It’s a bit like Discord or Reddit. They can join servers dedicated to activism, technology, gaming and other topics.

Gamers and activists aren’t cultural monoliths, of course, but these servers could foster specific attitudes which call for specific marketing strategies. Knowing the consumer might focus the strategy, but it also complicates reaching a general audience.

Servers also break up ad buying and delivery

Mastodon had more than 1.5 million monthly active users spread across 4,600 servers, as of Wednesday. Servers can link to one another and create a larger network, but given how few brands are on the platform, it’s not yet clear how ads will be bought and served to such a generally divided audience.

Each server has its own rules

Mastodon servers have different owners with different approaches to moderation. Once a user joins a server, they see a list of every rule they must follow. Some lists are lengthy and comprehensive while others have three or four general points about respect.

As non-existent as brand safety has been on Twitter, brands and their PR agencies could be opening themselves up to similar concerns depending on what server they join. As Richard Edelman wrote in his Thursday blog post on Mastodon, “There are brand safety concerns to consider as there is no central authority to ban spreaders of hate speech given it’s a fragmented network.”

No paid posts

Mastodon is ad-free at the moment, which means that brand posts aren’t promoted through paid posts. If a user is going to see an ad, they have to see it coming directly from the brand account.

Combining that fact with how spread out everyone is on Mastodon, it’s much harder to make your posts seen by a wide audience.

Journalists are showing up

Hundreds of journalists from prominent outlets are joining servers dedicated to their respective beats. For those seeking earned media love, the potential is there.