Access to your library continues to be available with free apps on phone, or Windows, or a newer Kindle as well as any browser, so the loss of support of 14 year old mobile devices doesn’t seem like huge news. There can’t be too many still in use even.
I would expect most of them have had their batteries fail long ago. Especially if they were disused for an extended period of time.
The article appears to be about “Kindle for PC.” It does look like there’s a Windows 11 app, though, for folks who’ve switched to the post-QA OS.