Earlier quoted context omitted.
I don’t see Apple having access to keys there. Could you point it out? CTRL+F for “key” came up with 7 results but nothing to suggest Apple holds them and can decrypt. Apologies.
There's a section about half way down that lists all end-to-end encrypted data (keychain, health, payment data, ...). By implication, all other data is not end-to-end encrypted. That includes iCloud drive, photos, calendar, contacts and mail.
Specifically listed as encrypted in transit and on server:
- iCloud Drive
- Photos
- Calendar
- Contacts
Only mail is not according to this support article.
Edit: I see the omission now. These things are not listed under the end-to-end section.