Green Door 4K only available from the US

We’ve watched Green Door on Blu-ray. It was bought it for my wife’s parents Christmas present in 2019 and we were able to borrowed it. Great film loved the colour palate particularly the cars. Decided to treat ourselves to the 4K version having looked at the technical reviews there’s an uplift in picture performance. My copy arrived today but from the USA. Just curious, does anyone know why it’s not available in the UK?