Yepp. It's obvious...
First, it might have helped if you could have matched the grain direction. Even more if you could have found a piece matching the grain pattern - which by the way can be faked using a pencil crayon.
Second, @ScottR recently showed how he patched a flaw using a more oval shaped piece but that method requires gouging beyond at least my skill set. YMMV
But seeing that it's that large I suppose the edges would be more or less visible no matter what. Which is why I suggest you to think about making that a feature. A round piece of contrasting wood, maybe with your logo, or even a coin inlaid would give that round patch a purpose. Further, depending whether that's the bottom side or the top of a lefty, or just a mirrored phone photo, you might use that as part of the control cavity.