Its going to be Lucas burning the materials so the OT stays at 1080p just like his precious Prequels…
AOTC and ROTS are in 2K, which is slightly higher than 1080p.
Keep in mind they cropped a native 16:9 image to 2.35 aspect ratio, so that’s throwing some pixel real estate out the window.
I’m sure someone more knowledgeable about the cameras used on AOTC and ROTS will chime in with the actual technical specs of the cameras used, and the video format the footage was recorded to.