Similar to the shit they're doing on Audible, too. If you want to be part of their subscription service, then you cannot sell your book anywhere else, including your own website, or have it available in libraries. And if you're not part of their subscription service, then part of your sale proceeds gets diverted to authors who are part of the subscription service [0].

[0] https://kindlepreneur.com/audible-royalty-changes/