Until yesterday I saw everywhere the normal "simple" user card under questions and answers. It has the small avatar, name, rep and badge count. But this changed now and I wanted to read again the page explaining the different appearances of user cards, but I can't find the page.
What I'm seeing now, is some users still having the small user card, which does not expand when I hover mouse pointer on them, while some users having the small user card but it does expand when mouse-over, and a third kind that only shows the small avatar/icon but no other information until a mouse-over brings up an expanded user card. Why did this happen? Where is the page that explains the different versions of user cards?