There's going to be a lot of blame being thrown around if the movie underperforms, but it seems like most critics think that Zhao's style just didn't mesh well with the genre. Marvel's taken a chance on other indie filmmakers before, but the majority of them were pretty experienced, knew how to shoot action, and weren't overly serious. Zhao, on the other hand, has only made bleaker dramas and has never written anything for a commercial studio before rewriting the Firpos. It makes sense that the movie allegedly uses flashbacks, exposition, and melodrama as a crutch - because those are staples of a different genre.

I think Zhao is insanely talented and am genuinely curious to watch Eternals for myself, but I think this goes to show that directors need to collaborate and trust in their writing partners when they're working outside of their comfort zone. I also think that she might be better suited for darker, more contained material if Marvel (or DC) rehires her.