The administration and maintenance of Microsoft Exchange Server to ensure secure, reliable, and efficient email and collaboration services across an organization.
Firstly make sure you have performed the steps correctly introduced in the official document: Migrate consumer Google Workspace (formerly G Suite) mailboxes to Microsoft 365 or Office 365
And please note that, Google sets the threshold that only 2 GB may be transferred per day. So you may try reducing the migration users to see if any help.
In addition, if the suggestion above still not working you. You could also open a service request to o365 to see if any error related to the backend, what‘s causing the error for many times.
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