T165854: Change OOUI EditPage inputs to keep the old 'id' attributes on the <input> elements wanted to make sure that the ids stay the same in OOUI mode, but it seems that some of the wrapper ids leaked into non-OOUI mode, breaking scripts in the same way as it was meant to prevent.
On https://de.wikipedia.beta.wmflabs.org/w/index.php?title=Benutzer:Schnark&action=submit (still non-OOUI mode) I have <input id="wpSaveWidget" inputid="wpSave"> and similar for the two other buttons. Summary input and checkboxes have the correct ids.