We are in the process of testing migrating data from our current SP 2013 on prem site to a new SP 2019 on prem site via a 3rd party tool. In one of our tests we migrated a list that has a user who created a list item and who no longer works for us and subsequently is not in our Active Directory any longer. We noticed that on the list, that users metadata, e.g. "Created By" and "Modified By", was replaced with the admin account that is running the tool. Other list items made by current employees show properly.
Can this be fixed by backing up the User Profile list from our current environment and restoring to our new environment.