> Would you say that no desktop app that saves its key can ever qualify as end-to-end encrypted?
I would say that no app can qualify as end-to-end encrypted if a large fraction of users send their data to the maker of the app in a form that can be decrypted by the maker of the app, regardless of the reason.
> iOS programs choose how their data is backed up.
Well desktop apps don't. Would you say that no desktop app that saves its key can ever qualify as end-to-end encrypted?
> And besides, iCloud is made by the same company, it's not a separate entity.
I'm not convinced that's relevant to whether the encryption is end-to-end or not.