%{issue.sprintEndDate}

When cast to text, the output depends on the jira.date.time.picker.java.format parameter set in your Jira instance.

19/Mar/20 1:38 PM would be returned for dd/MMM/yy h:mm a

If you want to return a number instead (a timestamp which can be used in several functions, see Dates, times and time zones), remove the leading % character in front of the field code.

 You will not be able to do this in the basic mode. Learn more about Parsing modes.