I haven't seen this behavior talked about before, but I have 4 pinned tabs, one of them being macrumors.com. There is this behavior where when I hover the mouse over the URL field, that the page's web icon disappears, and the whole URL shifts to the left, and 99% of the time, when I click, I end up clicking the SSL certificate lock icon, that has shifted left to be right under the mouse cursor. I have submitted to Apple Feedback...