Birdman's VFX supervisor Ara Khanikian explains how Michael Keaton's pseudo-superhero movie return changed VFX with its techniques. Before it was announced that Keaton was returning as Batman for The Flash, the closest he came to returning to the superhero genre was in Birdman. The film premiered in 2014 and is a black comedy that follows Riggan Thomson (Keaton), a washed-up actor trying to score another win for his career after it peaked when he played a superhero named Birdman 20 years earlier. While Keaton portrayed the Birdman hero in Thomson's fantasies, it wasn't quite the same as his Batman role, but it did impact VFX.

https://screenrant.com/birdman-movie-michael-keaton-vfx-technology-change-volume/