It’s like in Nolan films, there are multiple framings and cameras used within one scene-35mm anamorphic, IMAX, VistaVision, etc. Dan Mindell didn’t need to use IMAX camera for all the shots as they are really heavy. For shots with a lot of movement and within interiors, or close-ups, he’d just use the much lighter 35mm cameras, probably handhold them. The IMAX portions would naturally be mostly exteriors and plate photography.

Even if there was no aspect ratio shift during the falcon chase scene, it makes no sense to use a cropped pan & scan shot with less detail. So, for any shot within the IMAX scene that is cropped, it’s ideal to use the 2.35:1 footage instead.