#4. Grant Term Store Administrator privilege to service account/app profile

To migrate managed metadata columns with terms, the source and destination service accounts/consent users of delegated profiles must be added to Term Store Administrators before the migration.

Go to the Term store page in SharePoint admin center and add the migration service account to the Admins.

URL of the Term Store management: https://{TenantName}-admin.sharepoint.com/_layouts/15/online/AdminHome.aspx#/termStoreAdminCenter.