No one cares about the big CGI battle at the end that's been done to death: Spectacle Fatigue.
It's not actually Superhero Fatigue.
Replying again to add to this...
One of the problems the movie theaters have now is that Spectacle - the big screen and sound system - is their primary differentiator over home presentation. If you are correct, we are fatigued by the one thing movie theaters do really well. And that's rough for their business.