Currently, on the top backlog page, when there is a lot of releases or backlog items and the page is being scrolled down, the header is not pinned.
The releases headers being sticky positioned, we can see the content pass between them and the page header.
On the other pages, such as the planning view, the header is pinned, so this "visual issue" does not exist.
Adding the class "has-sidebar-with-pinned-header" to the page body will fix it.