See
https://fr.wikipedia.org/wiki/Utilisateur:Elitre_(WMF)/Prove5?veaction=edit
https://it.wikipedia.org/wiki/Utente:Elitre_(WMF)/Sandbox_VE8?veaction=edit
and https://en.wikipedia.org/wiki/User:Elitre_(WMF)/Sandbox3?veaction=edit .
The widget behaves as if you are attempting to create the article "API".
On en.wp it also provides a direct link to create Special:Mypage/API.
Version: unspecified
Severity: normal