To adopt ADP on CloudKit we have to use the new fields available for this purpose. The problem is the APIs are available starting a specific iOS and macOS release and we if adopt it we have to drop support for a considerable half of the currently supported OSes. As @HumbleBear wrote this doesn’t mean your online date and the communication between your device and CloudKit is not encrypted but Apple holds the keys.
Single notes encrypted in Bear are already e2e on top of Apple’s encryption.