The rotation of the gear, and the shadow on the right side of the icon makes it look off.
I used to play in windows mode, but ever since I noticed the icon like that I've been playing in fullscreen so I wouldn't see the icon on the bottom of my screen.
It's a very minor detail that probably most players won't even see or bother with.
Screenshot of when there is no focus on the application.
When there is focus, it looks like the icon is more to the left.