According to the latest beta of iOS 14.5, it has been discovered that users will be able to change Siri’s default music player. Right now, whenever you ask Siri to do something, by default it will attempt to use Apple’s own services. So if you asked Siri to play a song, it would try to stream it using Apple Music through the Music app. This means that users who use other services like Spotify, Deezer, YouTube Music, and more won’t be able to use Siri in that way.
However, iOS 14.5 will change that where users will now be able to choose from various music streaming services and apps in which Siri will choose to use. That being said, the feature in the current beta isn’t working quite the way it’s supposed to as some users are noting that it only works with specific phrases, and that sometimes it will revert back to Apple Music.
We can only assume that this is due to a bug since it is the beta version of iOS 14.5, so hopefully Apple will have it sorted when the update is ready to be released to the masses.