A scheduled page has its page restrictions automatically changed. Here's how.

When a page (or blogpost) is scheduled, view restrictions are added to the page for the users and groups who can edit pages (or blogposts) in the space. These view restrictions will replace any previous page view or edit restrictions. One exception: if the page has restrictions in place because it was created under an automatic publishing workflow, those restrictions will be preserved.

When released, the view restrictions are removed from the page, unless an automatic publishing workflow applied the restrictions on page creation and the workflow is not complete. Conversely, when the automatic publishing workflow for newly created pages is complete, the view restrictions won't be removed from the page if the page is also scheduled and is outside the scheduled window. This means that a scheduled page won't be released if created under an automatic publishing workflow that isn't complete, nor will completing the workflow release the page if it is still subject to being scheduled.