Hello,
Today iOS 16.3 has deleted all my books in Books App, it's now just an empty app with categories and 0 books or PDFs.
2000+ books and PDFs has gone. Collection I was creating for the past 5 years. 95% hand picked and sorted to almost 150 categories, including articles, which I've converted to PDFs and custom ePubs.
iCloud wasn't enabled for Books. I was making full backups with iTunes, but somehow Apple stopped including content from Books to backups. For third-party reader everything is backed up.
How crazy is that? Apple made AI in photos, but can't keep users data safe

Why not to:
- Warn user when there is not enough space
- Ask if user wants to delete something manually
- Ask for confirmation when iOS wants to delete content in Books
- Make a log about it! No log in my case in Privacy & Security -> Analytics & Improvements -> Analytics Data. Nothing about deleting the whole Library with books
- Delete a few books, latest/largest
- Backup database where I can at least see titles for further recovery!
Nothing from the list above. iOS just silently deletes all my books.
The funny part that iOS hasn't cleared caches for some apps (10Gb+ in total), instead it deleted all books. Unbelievable.