When an administrator switches methods from Authorization Code to Client Credentials, how is data related to the previous data sync managed?

When an administrator switches methods from Authorization Code to Client Credentials, how is data related to the previous data sync managed?

When migrated from the Authorization Code method to Client Credentials, the user will not have access to the Tasks module of Microsoft 365. Also, the complete data of the organization in the Contacts, Events, and Mails modules can be accessed.