Nowhere in the linked site that I’ve been able to find does it explain clearly that iCloud backup undermines on-device encryption.
The point is that the deep compromises made inside iCloud Backup are hidden from the user and (at best) buried deep in technical documentation. So deep in fact that I can’t find any mention of it on that site at all.
Storing an essentially plain text copy of your entire phone on an Apple server is the default setting. You have to actively find the setting to enable the security feature (not having Apple give your data to any gov they want) by disabling another feature that makes no mention of security (backups). iOS is not safe.