Why does the OGP content differ depending on the Manual?

The information on the Manual cover is displayed as OGP (the title and image that are automatically shown when a Teachme Biz Manual URL is posted on social media, etc.).

However, if a viewing restriction that depends on the user is applied — such as the Manual belonging to an Internal folder or having Folder IP Restrictions set — the Teachme Biz service name and logo image will be displayed instead.