Likely related to T212340: VisualEditor silently changes <references responsive="1" /> to <references responsive="" /> it was reported on the German-language Wikipedia's feedback page that [[https://de.wikipedia.org/w/index.php?diff=183708510&oldid=183690864&title=Khasi&curid=255455&diffmode=source|the VisualEditor sometimes changes <references responsive> to <references responsive="">]].

However, this does not always happen, e.g. [[https://de.wikipedia.org/w/index.php?diff=183731396&oldid=183589627&title=Netzpolitik.org&diffmode=source|in this test edit <references responsive /> was left this way]]. (It might be that there is a difference between the cases <references responsive> and <references responsive />.)