I mean obviously from like pro tools or whatever was used to create the song, but how do people like us get our hands on them? do people actually pay for these stems/multi tracks just to have them leaked? this question came to mind when I came across RiotLuke1 on YouTube who makes acoustic versions of songs which are just a piano instrumental and a mix of the lead vocals stem and Adlibs stems.
for example, his "Me & the Rhythm" acoustic


I also came across a soundcloud page that does acoustic versions in a similar way. they did "Touch It" by Ariana grande and "PILLOWTALK" by Zayn and I love it and am wondering if the stems for the songs are floating around somewhere??
https://soundcloud.com/amandeep-saran1/ariana-grande-touch-it-acoustic
https://soundcloud.com/amandeep-saran1/zayn-malik-pillowtalk-studio-acoustic