It wasn’t any one specific item, but with all the creature names that weren’t super obvious, the acronym (forget what for) and the engram scanner there was a lot of stuff that just wasn’t immediately clear what I was reading about. If it just wasn’t all those at once it wouldn’t have been noticeable but (this is hyperbole) it felt like every proper noun was something I needed to reference somewhere else.
I’m sounding more critical than I intend to be so take this with a grain of salt.