Sometimes we have to temporarily semi-protect a pending changes protected page due to really excessive vandalism, but we'd like to keep the stable settings unchanged for later, or we temporarily semi protect a page and also add pending changes protection but a bit longer to test the water.
So when a page is both pc-protected [autoreview=autoconfirmed] and semi-protected (or higher), pending changes shouldn't be visible, in the sense that we don't get the pc icon at the top right of the article and the pc edit-notice. For [autoreview=reviewer], it should deactivate on fully protected pages only.