Khan Academy: Stored 'undefined' Cross-site Scripting

Hello KhanAcademy Security Team, I'm rootbakar, I found an XSS bug on 'BIO' in the profile, I used payload XSS "/load=promptdocument.domain;"/load= prompt document.cookie; after I save it appears there is no trigger from the XSS, but when I try to change one of the values in the profile form and...