In https://www.wikidata.org/wiki/Property:P791 the examples of use of the property show a link only while the property is loading; then, when the page is fully loaded, the link disappears. I've tried with three different browsers (Chrome, Mozilla, Edge), both logged-in and not logged-in (so it's highly improbable that other gadgets interfere). The same also happens in items containing the property (e.g. https://www.wikidata.org/wiki/Q3639565). At least another user say he visualizes correctly the links (see https://www.wikidata.org/wiki/Property_talk:P791#Again_on_URL_di_formattazione_(P1630)).