Except why? Why would an advanced multi million year species that show a clear technological advantage suddenly resort to subterfuge? There's no indication it was necessary against the Guardians who soundly beat them. Why would an insect like hive mind who clearly have zero problems just throwing enough numbers at things as a military tactic suddenly change things up?
That seems to more point to me that it's either a manipulation from The Club for their own personal gain, or the situation is true and there has been a societal upset in Thargoids.
Well if it wasnt subterfuge and the Oresrian Klaxian Civil war is real, then the Oresrians have already come to Humanity to learn better tactics to use against the Klaxians, so already past the just throwing enough numbers at things as a military tactic.
The Guardian logs suggested that the Thargoid were unprepared for a conflict of such magnitude with the Guardians.
They were forced to withdraw against Humanity by the Mycoid last time.
I would think an advanced multi million year species that show a clear technological advantage will plan to adapt, however "unsuited" to adaption they might be, as twice a clear technological advantage paired with just throwing enough numbers at things has not worked.