The Tantive IV in ROTS, like the rest of the film, has a yellow tint and that segment in particular is over contrasted. Also, in the OT, C-3PO is usually covered with some sort of grime that dulls down his finish to prevent the film crew from showing in the reflection. They removed it in post production on ROTS so he is even more gleaming than usual, but even with that major change in appearance, you can tell the shot has major lighting differences than in 77. He also looks more brassy than gold, but that seems to be just that shot, maybe to emulate the distorted version we see on Blu-ray. Some of the PT seems to match that flawed color pallet. But they seem to have used the original colors when creating the sets and costumes.