It's included in iCloud backups, just not toggled to use end to end encrypted iCloud sync (in which case iCloud backups would back up the decryption key). See

It's included in iCloud backups, just not toggled to use end to end encrypted iCloud sync (in which case iCloud backups would back up the decryption key). See https://support.apple.com/en-us/HT207428 https://support.apple.com/en-us/HT207428, https://support.apple.com/en-us/HT208532 https://support.apple.com/en-us/HT208532, https://support.apple.com/guide/security/security-of-icloud-backup-sec2c21e7f49/1/web/1 https://support.apple.com/guide/security/security-of-icloud-..., and https://support.apple.com/en-us/HT202303 https://support.apple.com/en-us/HT202303