So, it does say that not even Apple can read your data, but it also says it's protected by "end to end encryption", which if Apple can't read your data, is absolutely nonsense usage of the term.

"End to end encryption" means encrypting the data at one end, and decrypting it at the other end. That's literally the NAME. If they're not doing that, the term is completely nonsense to use. They might as well say they have fat-free encryption. What they're really doing is storing an encrypted file that you hold both keys for. And IF that's what they're doing, that's actually fantastic - far better than end-to-end encryption because only you can decrypt it. But they're not inspiring confidence by COMPLETELY misusing a term that has nothing to do with what they're doing.

The other point is, if those keys... if you have to manually copy those keys over between all of your devices? Great. You're actually protected. If, however, you just connect to your Apple account and now you can get your files out of iCloud? That means that Apple DOES have your decryption keys SOMEWHERE, because otherwise they couldn't send them to your other devices, which means, sorry, whatever they're promising, they DO have the ability to look at your files if they're motivated enough.