Don’t throw away your Kindle, Jailbreak it and take back ownership. Make your Kindle even better with KoReader and other apps. If you wanna see whats possible i recomment this Yt video. If you wanna get started here are all instructions: https://kindlemodding.org/ Don’t let it scare you it seems complicated but its just a lot of (easy) steps. So definitely possible in <2h.
Amazon disabled the the possibility to download the books you bougth onto your pc and sometimes they change or delete books wich will change the books on your kindle. In the yt video linked the person says the changed for example the cover of books to advertise a new show based on the book.
And jailbraking helps getting the books off the device?
No but makes it easier to sideload and prevents amazon from owning/changing/deleting “your” books
You can still sideload afaik. You send the epub to the Kindle email. That still works.
My kindle hasn’t been online since 2012. Just buy DRM free books or pirate them, and then transfer via cable. None of the firmware upgrades introduced anything useful.