I've been told repeatedly that I show the second face to early, well before I actually close the app, usually starting around the time we're discussing signing off.
As an American. I'm so, so sorry. It's a plague over here. It's definitely a cultural thing. The ways the US functions at it's core demands it, in its hyper-competitive work landscape. Thankfully, a lot of Americans understand how fake it is and hate it, too. It tends to mostly present itself in more "successful" individuals in the States.