The degradation in the user experience has been happening for quite a while. I have given up reporting any problems with the reader as they either can't fix the problem or just don't see a problem that they should fix. Part of the problem is that the reader, for Amazon, is store-front advertising whereas the poor end user just wants to read a book.

The app reopens to where I am reading when I open it, unless I've manually quit the app. If I quit the app, the it still frequently opens to where I was last time, although there may be some reset period after which it opens the 'your library' page. In that case, an icon representing the book I'm currently reading is visible in the bottom left, and I can open it with one tap.