That’s almost certainly due to the temporal noise reduction in the original Blu-ray. The algorithm that was used often couldn’t handle an object moving against a static background, leading to the background getting ‘smeared’ around the moving object.

This issue is fairly ubiquitous throughout the film (examples that comes to mind are C-3PO trudging behind a dune and R2 moving down the canyon right before he’s shot), but it’s more noticeable here since I’ve brightened the image so much. There is actually one shot in which I fixed this issue, by rotoscoping in detail around R2 from the SSE:
https://diff.pics/5H4o2DcPEHdM/14