The Report widget on Dashboards has a Viewer Mode, which dictates what data viewers of the Dashboard can see - only data from sheets they have permission to view, or data from sheets that the last widget editor has permission to view.
Adding the Viewer Mode with the same options to Reports would be incredibly helpful. As an example, here is a current scenario for our team:
It seems a bit ridiculous that I could create a dashboard, add a report widget to it, and set that Viewer Mode as "Last widget editor," and they would be able to see the data. (BTW - This does not work as a solution because viewing a large report and Gantt on a dashboard is incredibly user unfriendly.)