Super admin users can enable settings so deadline date should always be required when creating a job ad. This is an optional settings for companies.
When enabled, jobs in your company can not be created without a deadline.
To activates this go to Profile - Company settings and scroll to the bottom of the page where "Deadlines" is and only need to turn on the toggle to enable deadline required and the setting is auto saved.
Now when creating a new job ad the deadline date is a required field and it is not possible to publish the job ad at your career page without setting in the date.