I read this on Pitchfork [1] couple of days ago, their source was Music Business Worldwide [2] and with a provided US patent: Identification of taste attributes from an audio signal [3]

[1] https://pitchfork.com/news/new-spotify-patent-involves-monit...

[2] https://www.musicbusinessworldwide.com/spotifys-latest-inven...

[3] https://patents.justia.com/patent/10891948