Perry told Billboard the album was a result of growing as an artist and going from her 20s to her 30s.
Swift famously removed her music from all streaming services shortly before the release of her 2014 album "1989", decrying the services' royalty payments. Not to mention many people just listen to music videos on YouTube as well.
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"I'm not willing to contribute my life's work to an experiment", she said before citing complaints of skewed pay scales that make it hard for writers and less well-known acts to make money from streaming. Amazon Music also retained access to Taylor's back catalogue as well, though they will be adding her latest release tonight. She wanted to reflect that in her music on Witness, which she described as "purposeful pop. 360-degree liberation: mental liberation, sexual liberation, negative liberation, spiritual liberation", Perry said.
At the height of her pop powers, Perry scored a record-breaking six USA number one singles from 2010's Teenage Dream album.
Perry first opened up about her and Swift's feud during her appearance on James Corden's "Carpool Karaoke" last month. Perry also said she attempted to speak with Swift about the issue, but Swift shut her down.