It mentions style as being among the data points used, along with personal details, though if your hidden account is used for things like whistleblowing or niche erotica, you may not be mentioning telltale biographical details at all often, while you can’t help writing the way you write, with numerous unconscious choices between alternative ways of phrasing things, which will be the bulk of what it has to work with.

Of course, that doesn’t mean you couldn’t slip up, so if you don’t want your posts traced back to you, also look out for any details you’re leaking and file the serial numbers off them (and perhaps rig up a way of delaying your posts outside of your waking hours).