Going to https://phabricator.wikimedia.org/project/reports/5/ there is this large date/time span selector at the top.
It only applies to one single string of all the stuff shown below: "Tasks completed this ...: X".

That's not obvious.

And probably also a waste of space, given how irrelevant it currently is.

This is custom downstream code in https://phabricator.wikimedia.org/source/phabricator/browse/wmf%252Fstable/src/applications/project/controller/PhabricatorProjectReportsController.php