Visually mark the fact that empty date fields with "empty is today" enabled have current date as default value

The problem is more noticeable in edit mode when a date input has an empty value and the user might not understand that leaving it empty will actually set the current date.

It would be a good idea to use something like a placeholder (with grayed text color) to show the implicit value of that empty date field, if the date property has set to use "empty is today".