Books purchased through Amazon are protected against copying and distribution by a level of digital rights management that can no longer be bypassed.
This prevents people who have purchased a digital book from reading it on non-Amazon devices.
It’s equivalent to Amazon selling you a physical book that can only be read by the glasses they provide.
Until now I’ve been able to successfully remove DRM from Amazon books using Calibre and DeDRM_tools but have reached the end of that line. Going forward I’ll be purchasing books from Kobo Books and Google Play.