Maybe your right I’m not sure now that you point that out but his looks different than mineI think what you are seeing as a grommet or washer is in fact a rim cast in as part of a one piece thru bolt head. I assume you are talking about the left or brake side of the thru bolt. You can see that outer rim very clearly in the first photo by the OP. There is no washer that I can identify on the right side. If I am missing something, please explain.