"Ahead of
True Detective's second season, the press publicized rumors that creative differences had fueled personal hostility between Pizzolatto and Fukunaga; the former denied the rumors, while the latter declined to comment.
[31] Pizzolatto retained control of the writing process but Fukunaga left, and the second season's eight episodes were instead variously handled among six directors."
This is all I could find in the official Wikipedo article, but it was quite big news at the time. I like how they use a lot of weasel words here, even though it's plainly obvious there was some friction behind the scenes. From what I recall (provided this isn't a Mandela effect), Pizzolatto's original plans were to prominently feature a relatively well-known abandoned underground city in Season 2 as the place where the villains would conduct their business of child trafficking. Before it could be produced however, Pizzolatto suddenly "changed his mind" and we got the generic story we ended up with.
FOUND IT:
https://collider.com/true-detective-season-2-occult-aspect-dropped-new-posters-revealed/
Just as I was about to hit post.