We are using the living status report in the Modern UX. That is, the tab "Status" within projects. We have custom attributes defined in the Project object. We expect that these custom attributes are automatically copied over from a Final report to a Draft report when a report is published.
Version: 16.0.0
Values of only those custom attributes that are displayed as widgets in the "Status" tab, are copied over to the new Draft report, when a publish happens.