There's no issue with permissions as product is working as it supposed to.
Investigation has found that:
- Team was migrated properly with Owners and Members populated in the target Team. Accounts were migrated and/or matched by ODM previously.
- linked Sharepoint site didn't have human owners in the source and ODM added a service account as an owner in the process of migration, which is by design
- although target SP site does not list human owners directly in the SharePoint Admin UI, Site Permissions, performing Check Permissions in the Advanced, and specifying one of the Team's owners show that this person do maintain an access.