impossible to answer but possible to speculate
they have not cracked aacs 2.0. and i dont think aacs1.0 was even cracked. rather they have figured out a means to access the encryption keys to decrypt the disc. aacs 2.0 key mgmt is different than 1.0.
once you have the keys you need to write the code to decrypt the content.
my guess is still they found a hardware exploit for uhd drives that exposes the keys or makes it possible in some similar manner. similar to the fairly recent sacd hack for players using specific mediatek chipsets (oppo 103, 105, various pioneer players). it is not a crack. it is an exploit in the hardware to read the decrypted information and stream it to a program that writes it to disk.
this would explain why you have to own specific drives. i bet there is a common chipset in these drives.
all conjecture of course. but it works and 32 discs later i am satisfied