There is a section that says:
Use a rule to mark users as migrated. This is not a hard requirement, but it does protect against one scenario in which a user changes their email address, then changes it back to the original email address. A rule should call out to the legacy database to mark the user as being migrated in the original database so that
get_usercan return false.
In the context of a rule, is there an out of the box way to tell if a user was migrated vs. newly registered directly in the Auth0 managed database? The way that section of the docs is written implies there is some straighforward way to do this.