I saw the description
You may verify the refresh token up to once a day to confirm that the user’s Apple ID on that device is still in good standing with Apple’s servers.
I have two question about the description:
refresh tokeninstead of
access tokento confirm the user's Apple ID is still in good standing with Apple's server?
Update on 10/17/2019:
For apps running on other systems, use the periodic successful verification of the refresh token to determine the lifetime of the user session.
I also saw the description above in in https://developer.apple.com/documentation/signinwithapplerestapi/verifying_a_user . I think
periodic is also conflict with
once a day.
These are good questions. Too bad that no one replied to them since october. I would like to know the answers too.