Some kinds of data are always end-to-end encrypted, even with the default standard data protection:
Passwords and Keychain
Health data
Home data
Messages in iCloud (only when iCloud backup is disabled)
Payment information
Apple Card transactions
Maps
QuickType Keyboard learned vocabulary
Safari
Screen Time
Siri information (excluding Siri Shortcuts)
WiFi passwords
W1 and H1 Bluetooth keys
Memoji
Also in the article "In December 2022, Apple introduced new security features, including Advanced Data Protection, which applies end-to-end encryption to several additional kinds of data. Apple calls this their “highest level of cloud data security”. Advanced Data Protection generates encryption keys on each of your iCloud-connected devices and encrypts eligible data before uploading it to iCloud. Apple does not have access to the keys required to decrypt that data."
Later in the article they say: