The fact it requires a specific piece of software, even on desktop, puts it one step from (old) Twitter to me.
Even things like Discord - while very much not the same in other ways - has a web version that runs in a browser. Ditto the early 00's instant messaging apps.
Also, the decentralisation seems to all be under the control of the one company(?). They say "no single entity controlling it" but there's not much further detail. I might be mistaken, but it doesn't seem like the Fediverse's version of decentralisation, at least at first glance.
Moving further(?) into tinfoil hat territory: The founder's name is very similar to that of a late Reddit founder, which is worth a double-take. Funny coincidence? Fake name? Either way might be playing on the coincidence? etc. etc. Hard to tell. Dude's probably legit, right?
b) A few of the web links for it were in Chinese, but that's probably a red herring. Translation suggests people in China are using it to get around certain internet issues.