Private Relay also works because it's on by default for everyone paying for iCloud (including everyone just on the 0.99/month tier for photo backup) - so Apple

Private Relay also works because it's on by default for everyone paying for iCloud (including everyone just on the 0.99/month tier for photo backup) - so Apple can use it across their apps (e.g. loading images in Apple Mail) and it doesn't let you single out privacy conscious users!