The Romanian landing page for commons, https://commons.m.wikimedia.org/wiki/Pagina_principal%C4%83 , looks different following the user and the moment of the visit: sometimes the page looks a lot like the desktop page (horizontal scroll, but all the content is there). Other times, the layout is improved, but the upload link is not there. I had the same experience with the English page, although much less frequently
I thought I had linked the issue to the login process (with the desktop-like appearance when logged out and the incomplete mobile view when being logged in), but @Base reports seeing the desktop-like layout while being logged in.
The layout should be consistent throughout the whole navigation, regardless of whether the user is logged in or not.