If you have a decent library at Kindle and want a DRM-free copy, I'd download it now.
Joke's on them I've never bought a book from the Amazon store! It takes a few minutes to drop files on it via USB.
I've now moved to an Android eReader (Boox Note 7, for example [1]).
I can just get the Ebook or PDF files and transfer them via Calibre, simple as that, and I can also download any Android app i want. There are tons of apps out there that support eInk screens.
And even the ePub readers that have been left behind can still work with new books.
I lend books legally (library membership), strip the DRM and convert it to mobi. There's just no way I am reading books on my phone.
After all the kindle is a hard disk with a nice screen.
This issue affects a wider range of devices, and is software-related. I'd guess at it being either TLS related, or something to do with updates to their DRM system.