APPLE INSIDER
Apple has clarified that a Siri feature in iOS 14.5 asking users to select a music service isn’t actually setting a default streaming platform.

The feature, first spotted in the iOS 14.5 beta testing cycle, pops up when users tell Siri to play music. The digital assistant will ask which music streaming service it should use, offering a list of providers that users can choose from.
Source: APPLE INSIDER