When you are logged out, and you attempt to edit a page, you'll get a prompt to login, if you choose to edit without logging it, your browser will make a request like this:
https://en.m.wikipedia.org/w/api.php?action=query&format=json&prop=revisions&rvprop=content%7Ctimestamp&titles=Gotham&meta=userinfo&uiprop=blockinfo&list=blocks&bkusers=&bkprop=flags&formatversion=2&rvsection=0
The request is missing any bkusers (notice bkusers=&) which means a list of unrelated blocks are returned. We should ensure that bkusers is populated before making a request to API:Blocks