There had been cases reported where incorrect tagging using the wikipedia tag caused negative side effects on data consumers.
In this specific example a lot of amenity=cafe brand=Starbucks had a link to the brand page of Starbucks.
As nominatim (a major search engine for OSM) has to rank results somehow it uses a wikipedia article as an indicator that the feature must be of some importance to justify its own article.
By linking a specific feature to a general article that feature inherited the importance. It showed up higher in the result list than it should have.
This thread is about fixing them:
https://lists.openstreetmap.org/pipermail/talk/2016-January/075432.html
Please keep in mind when you add tags to specific features that they have to apply to that specific feature. So no linking to a generic wikipedia article or website.
The “first” Starbucks cafe has it’s own page, so that got linked. The others have it removed as it applies to the brand, not the specific cafe. Similar would be other restaurants, shops or petrol stations. If the link is leading to a specific article or website about that feature the it is ok. Linking to the general landing page of the brand is not.
We could use “website:brand” for it if it is considered useful…