LPS-26221 a functional change was committed.
Default behavior is that when a new Announcement entry will be added then the display date property will be based on creation date. On UI this is showed as a checkbox(autoDisplayDate) which is checked by default. The Date widget is disabled by default.
If users want to set another display date in the futute or in the past they need to uncheck this checkbox. This result the Date widget will be active and the users can set displayDate.