This was reported on the German-language Wikipedia's feedback page and although it has no visible effect caused some confusion among editors.
Steps to reproduce:
- Go to the Internet Archive article or [[https://de.wikipedia.org/w/index.php?search=insource:/responsive=""/&title=Spezial:Suche&profile=advanced&fulltext=1&advancedSearch-current={"namespaces":[0]}&ns0=1|any other article with <references responsive="1" />]]
- Open the article for visual editing and make a small change such that Änderungen veröffentlichen... (Publish changes...) turns blue (e.g. delete and add back a character)
- Click on Änderungen veröffentlichen (Publish changes...) and select Überprüfe deinen Änderungen (Review your changes)
- Observe that <references responsive="1" /> was converted to <references responsive="" />