It’s perfectly aligned with the frame and has a string of perforations on one edge. So a physical object of some kind, surely?
A quick search of Attack of the Clones film cells for sale shows that they have a strip this same teal color along the edges (part of the audio). But the reason for this artefact will have to be explained by someone else.
Although if it is a real, physical object that somehow fell into the path of the scanner when they scanned the ON back in to create the final digital master (although I still have doubts they did such a thing since they kept going on about the purity and trueness of their pure digital master as well as an incredible rush for time, so would they really take pure digital master, digitally print out an ON, then scan that back in and then use the scan as the final digital master for the digital theatrical (and all future home) release?) it would seem surprising that it would fall in the way so perfectly aligned and just for so few frames (although perhaps someone spotted it and nabbed it out right away after having knocked it off a table into the path or something and the time was so rushed they had no time to start the scan again??). The potential performations also seem odd.
I still am not sure whether it is a real object that somehow ended up in the image or some digital processing artifact (I did notice on the UHD for ROTJ that in one frame you can see a perfect circle or fairly large size where the image is all totally smoothed out, like someone accidentally droped a large radius smoothing brush on part of the frame). And then there is this error in the first pressings of the Grease UHD where they applied some sort of ‘power window’ to enhance red and then forgot that Travolta’s head would pass through it for a few frames and you got this weird mistaken effect below:
original blu-ray:
initial UHD:
