Cinematography, edges of frame out of focus and barrel distortion
Barrel distortion makes straight lines look curved. In some scenes it's distracting. I think the photographic term for the focus issue is field curvature aberration.
Curious artistic choice to use lenses with such pronounced aberrations. These aberrations are more common in older lenses, so maybe that's what they are going for. To make it look like it was shot with crappy lenses in 1900.
https://imgur.com/gWlz0rY