I observe this when I call ‘/wiki/rest/api/content/{id}/permission/check’ endpoint, I get list of restrictions with User IDs, which are not added in parent level restriction.
In the UI it shows a warning message that “Needs access to space first. Contact a space admin.” or " Needs access to a [parent] first.",
but only through API it is difficult to know whether the users actually has access to the content.
API Documentation- https://developer.atlassian.com/cloud/confluence/rest/v1/api-group-content-permissions/#api-wiki-rest-api-content-id-permission-check-post