Incorrect language when not logged-in - "Download Night Builds" Page

When I've opened today a page with nightly builds (not logged-in), non-english language apeared.
When I've logged-in, the language changed itself to Polish. But the Polish language is still Polish, when choosing for example English, or Deutch. Side menu changes correctly, but page content not.
Screenshot in the attachement shows how the page looks to me when I am not logged in.

I think that this is happening: that page is choosing the language by reading the user profile country section (or language section),.