I think people just focus to much on the term digipack. The Proof (Compact Edition) is already a version of digipack, which is cheaper than the deluxe one. Also, even proof album can’t be done digipack as It still ended up to be at least 3 CDs. You can’t sell the 3CDs album less than $20, that is very stupid.
Regarding to the IFPI, if IFPI count Proof as a double album, BTS still get No.1 but they didn’t do it for last year Japanese album.