This is all a good point.
Purely coincidentally, the imminent next release of iOS adds new account recovery options: https://9to5mac.com/2021/08/06/how-to-use-icloud-data-recove...
> If you create a recovery key and can't access your devices, Apple won't be able to help you regain access to your account or your data.
That sounds like E2EE backups, but its impossible to know if that is truly the case until they provide more details.
> The service requires Apple to maintain access to your data to help you recover it. For your privacy, Apple can’t access or help you recover your end-to-end encrypted information, such as Keychain, Screen Time, and Health data.
Seems to suggest that there is no change to end-to-end encryption on iCloud.
The scariest thing about this update to me is that it makes one's iCloud account incompatible (permanently?) with iOS and Mac devices that are not on iOS 15 or Monterey.