Annotating example.com/index, I see all the same highlights on the sidebar but not on the actual text when I navigate to example.com/index#header.
Ah this is such a painful part of the current web. So many pages still use the # fragments to encode critical information about the page location. So it’s very hard to make an opinionated choice.
But maybe since using # fragments to do this kind of magic is not standard behaviour, we could also go the route of just removing the # fragments in an opinionated way.