Yeah, that probably has something to do with it. I heard Colfer wrote the Atlantis Complex in about a week…which would explain a lot. And the last one was a generic apocalyptic finale, which really wasn’t necessary. Something more low-key, like “the ultimate heist,” would’ve suited the series better.
A thought that literally just came to me: a better plot for the last one might’ve involved the two Opals working together to build an impregnable fortress, and Artemis having to find a way to break in.