I have an old Kindle Paperwhite where I both buy books from Amazon and sideload using Calibre and it has never deleted anything to my knowledge. It's usually i

I have an old Kindle Paperwhite where I both buy books from Amazon and sideload using Calibre and it has never deleted anything to my knowledge. It's usually in airplane mode, but I of course turn syncing on whenever I buy a book from Amazon, and it never deleted any of my sideloaded books. I wonder if this is a "feature" of new Paperwhites? If so, it would suck. I was looking to replace mine because it has the old micro USB connector that no other device I own uses, and so I must keep a cable just for it.