[sneak]

iCloud Backup is not end to end encrypted and is readable by Apple. Same again for iCloud Photos. The Apple-readable iCloud Backup contains the keys for your iMessages, which means Apple can read those in realtime as they transit the servers (due to relaying the ciphertext, and having the keys from the non-e2e backup).

Even if you disable iCloud Backup, everyone else you iMessage with will back up all your iMessages from the other end, because it is on by default.

The idea that Apple can't read your data is mostly false. They can see all your photos and read all your chats, and all of the other files and app data from your device. They can do this without your device or password at any time.

They do this for the US government without a search warrant to over 30,000 user accounts per year, per their own transparency report.