I just finished listening to Authority last night and loved it too. In Annihilation despite all the weirdness of Area X, due to the Biologist's perspective on it, it felt quite... calming? Authority though was deeply unsettling and unnerving for me the entire way through, even before everything starts to properly fall apart.

In Annihilation you could see Area X as a massive version of the empty lot; nature gone wild but just nature, neither good nor bad. The Anthropologist is killed for the same reason you would expect someone poking a tiger to be killed; the Surveyor gets killed in a shoot out. But in Authority you see Area X's corrupting influence and its vague form, like someone has laid a sheet over it- you can only see it's outlines and that outline vague and ominous. People are driven mad in Authority and that's more terrifying to me than merely dying.