At the moment, when a page becomes un-approve due to expiry time configured, no notification is sent. The page become un-approved from approved.
When editing a page, the state of approved page becomes un-approve and a notification is sent. Therefore, when a page is automatically become un-approve, no notification is sent.
To set up.
This request is for page-approval add-on to trigger notification when a page becomes un-approve due to expiry time/date.