Apparently, the HDR and Dolby Vision on the original saga films is pretty piss-poor. Disney also didn’t bother to even re-scan The Phantom Menace natively in 4K and instead used the original 1999 DI. This is provocatively lazy.
Hell, pretty much all their releases are sourced from 2K DIs. Even their flagship stuff like Endgame!
Thats sort of how the whole movie industry works, not just disney. For the film industry, 4K really has not been worth it until perhaps very recently. And its not really that big of a deal. You have films like endgame mastered on 2K and looking fanatastic on IMAX, its just not worth quadrupiling rendertimes for minimal benefit.
TPM was never going to get a full 4K treatment. This isnt like Star Wars 77 where the original elements can be rescanned and reassembled. TPMs master negative IS the original digital filmouts.
Its basically impossible to take one of these 90s-2000s films, rescan the elements and rerender the CGI. considering the difficulty of resourcing digital assets, vintage software and the hardware to run it, the huge number of addition plugins and programes that would make a film like that run. It would be easier just to make a new movie from scratch.
The film is locked at 2K forever and so is practically every other film from since then till nowish. Its not a big deal.