The adress bar on phones often is very small for URLs.
E.g. For this link Firefox for Android just shows me "connect.mozilla.o" and if I click on it, i see the end of the URL with "ostpage/board-id/ideas".
I can click on the lock-symbol and then on "connection is secure" to see the full URL. But it took me some time to figure out. Would be great to make it easier to see the actual URL you are on.