I was under the impression that all audio Spotify serves is heavily DRM-ed and can only play with special hardware decoders which respect the DRM? How did was this person able to play the encrypted audio? Does this not let them effectively rip music from Spotify?
Does your PC or phone have special hardware decoders from Spotify? Can you play Spotify on your PC or phone?
(one "interesting" case around that was that some OnePlus phones couldn't play netflix in resolutions higher than 480p, because despite the Snapdragon chip supporting the DRM format required for higher resolutions, OnePlus never paid the licence to use it - so their phones couldn't decrypt the video. They did relent later and said they will enable the functionality for users who send in their phones, and it can only be flashed in person at their service centre, not via an OTA update. I always wondered how many people have done that)