If you have a parent page and a child page and the parent page is restricted,
then the child page will (correctly) be likewise restricted. But if you MOVE
the child page somewhere else, it stays restricted even though its new parent
has no restrictions.
I was able to correct the situation by adding and then removing the same
restriction from the new parent page, which had the effect of clearing out
the child restrictions as well.

We have an internal company newsletter, which is created inside Confluence. First as a child of an under construction page (which has viewing restrictions) after which the newsletter is moved to become a child of the recently appeared page.

Moving the page does not change the permissions:

*the old viewing restrictions still apply
*when going to Info of the page you still see the old viewing restrictions and the name of the previous parent page
*when editing the restrictions of the page itself, the inherited restrictions are not mentioned, so there they seem to be displayed correctly.