It’s the same fundamental problem all the new social media sites have and why for instance there are a bunch of lemmy sites we’re defederated from. With such a small user base the initial users to join have an outsized influence on the content which then starts a feedback cycle. E.G. if the first users to join are a bunch of far right GQP nutjobs that spend all day posting about whatever the latest insane conspiracy they ran across, then anyone stumbling across the site that isn’t a GQP nutjob (or at least nominally allied with them like the various neo-nazi groups) is going to pass on it, and any marginal users who were on it previously would leave as it just becomes more extreme.
In particular these things tend to be driven by purges or mass exodus of other social media sites, so depending on who and why they left the previous site will tend to set the tone for the new one. E.G. when reddit purged a bunch of the more toxic subs a couple years ago and then there was a sudden crop of sites advertising themselves as censorship free reddit clones, only they all quickly devolved into complete cesspools. It turns out a certain amount of censorship and moderation is actually kind of important for maintaining a civilized discourse.