While observing three librarians editing each their own page, I noticed that they had uncertainties when asked to save their edit. I had to explain them they have to scroll the page, and exactly where to scroll: not the text area, the whole page.
Indeed, the save button is easily outside the screen, even without overly long copyrightwarning areas. We should always give a hint to users so that they know where to proceed.
Something as simple as a biggish button on top of the text area, linking the #wpSave anchor, might even suffice. Worth some prototyping and usability testing IMHO.
I filed a twin report for VisualEditor without realising: T90864