Recently changes were made to the process that shows the Wikipedia article in the about section to fix the fact all links inside the article pointed to the English language regardless of the display language.
I think it has had an unintended side effect. Previously if running the site in a language other than English, if the taxon had a Wikipedia page in that language, that would be displayed. If that language lacked a page, but it did exist in English, the English page would show.
Now if the running language lacks the Wikipedia article, it defaults out to EOL.
As an example change running the site to Danish and go to https://www.inaturalist.org/taxa/522781-Diurnea-lipsiella
Previously I would have seen the English Wikipedia article, after the changes I do not.
Tested in several languages and taxa so it is not a one off on the taxon.