Random text is getting dropped from Wikipedia oneboxes. See this example. Screenshot:
This occurs regardless of HTTP/HTTPS and of whether a redirect URL is entered into chat.
I initially thought the bug is triggered by
<span>s or other HTML formatting elements, but in the Burj Khalifa article's HTML source code, there is no formatting around one of the deleted words.
Possibly related to Numbers mysteriously stripped from inlined Wikipedia articles in chat, but this is not specific to numbers.