A new version of the Azure ShareGate migration tool app was created to add a small set of application permissions required for the new Copy mailboxes feature.
To use Copy mailboxes, you need global admin permissions, and when you connect to your tenant through that feature for the first time, you will be prompted to consent to a different version of the Azure app that includes the application permissions.
For more information on the delegated and application permissions used by the two versions of the Azure ShareGate migration tool app, see Which permissions does the Azure ShareGate migration tool application need?