Apple Music launched voluntary transparency tags for declaring AI involvement. Unlike Spotify's DDEX credits, these are optional: the label or distributor chooses whether to apply them.
That approach has an advantage and a cost. The advantage is that nobody has to rework an entire catalogue's metadata at once. The cost is that a listener cannot read anything into a tag being absent.
Our position. We declare wherever it is possible, even where it is not required. It is set out on our AI use page.