Everything listed in the second article, including iMessage in iCloud is end-to-end encrypted: AirPods pairing keys, Safari tabs/history, learned keyboard vocabulary, Home app, Health app, Apple Card transactions (not sure what the point of this is as obviously the bank, card network, many others have detailed records), Maps favorites, Memoji, Siri data, Screen Time data, and Wi-Fi passwords, and yes, iCloud Keychain.
The catch is that if iCloud Backup is enabled, the iOS device will make a copy of its private iMessage key and save it with the backup, rendering your messages accessible to Apple. This doesn't affect Keychain.
Other services such as iCloud Photos are not E2EE and are always readable.
The catch is that if iCloud Backup is enabled, the iOS device will make a copy of its private iMessage key and save it with the backup, rendering your messages accessible to Apple. This doesn't affect Keychain.
Other services such as iCloud Photos are not E2EE and are always readable.