It wasn't shot in Vistavision and pictures in the FTD book proves it. Regardless, this has always been a wonderfully shot film and if you're a fan of the film, try and find a copy of the book---it's fantastic!!
Agree completely, it would be interesting to know why Curtiz didn't shoot in VistaVision. Budget concerns? artistic choice?
As you said, we can enjoy a beautifully shot film in 4k and on BluRay in 2020.
Now, if NBCUniversal would step up and release the 4k restoration of Loving You (1957) that Redwind had completed but couldn't release - due to song clearence costs. Criminal that a 4k scan of Elvis's first starring role, and only 1950's film in color, is just sitting on a hard drive for no one to see.