When loading a page on mobile (tested on en.m.wikipedia.org in Chrome) the watch star consistently shows up a second or two after the rest.
I can reproduce this both on tablet mode (in desktop Chrome) and mobile mode (iPhone).
This element should render properly by default. It already has a regular link fallback (pointing to index.php?action=watch), but this is broken right now since the <a> has no content. It should presumably use the same icon throughout so that no visual change occurs.