There's a regression most likely caused by AF-1048.

The alert "Are you sure you want to discard unsaved data?" is displayed even when creating dataset (just before "successfully saved" notification appears).
In this case it also appears when leaving the perspective. In both of these cases the alert is "lying" as the data have been saved successfully and no further modifications have been done in the editor.

See steps to reproduce in video (just create csv dataset and save it).