https://preview.redd.it/ymeiumqyzj2c1.jpeg?width=1284&format=pjpg&auto=webp&s=4bbfc22f943b757a9be3249328ebeb2c060d23aa

Looks like you don’t have it purchased through iTunes, as there is the Disney+ badge right above the Play button. If you have it purchased, it wouldn’t say to open in Disney+. Try scrolling down on that page to see the purchase options

The iTunes Extras includes the alternative ending along with other deleted/extended scenes

https://preview.redd.it/nkfm1eduyi2c1.jpeg?width=2778&format=pjpg&auto=webp&s=ca7886e68157584d7f10095a6eb8ec578d8e916c