ODM Teams shows huge discrepancy in sizes between source and target, but no errors in the migration (4378676)

Teams migration not completing we have multiple Teams migrations that are failing to complete. There's a big difference in sizes, shown in GUI, between the source and target but migration was without any errors. Target Teams are live and actively being changed.

Initial Teams migration used "Latest version" for the Sharepoint content

There's no direct workaround for this issue as migrating "Latest Versions" first, will essentially lock that in place and will not backfill historical versions even when subsequent migration used "All versions" option.

As an indirect workaround, to preserve historical versions, it's possible to:

• create a new project with the same source and target tenants
• discover and match all accounts
• discover affect Teams using CSV file or perform a full tenant discovery, knowing what Team names/Sharepoint content is needed
• re-map the Team to the new target target Team using More dropdown menu. Or, alternatively, pre-create the target Team manually and map source Team to this target using CSV file
• if remapping was used, then perform a full Provisioning, so target structure will be created by Microsoft. It's recommended to wait about 24 hours before starting content migration
• if target Team was created manually and matched, please run Provisioning, using Merge selection whenever possible. Give up to 24 hours again before running the Migrate task
• Migrate the Team, making sure that "All versions" is selected

Note: the same mechanism applies to M365 Groups and Sharepoint files. Though, if the target entity (Team/Group/SP site) is not yet live, it's possible to remigrate the content, choosing "All version" and "overwrite" options.