Group Focus below reference element (prevent z-index updating)

In my design after clicking on the reference element the group focus appears and the top of it should be behind the reference element. But because of how group focus works, it always appears on top of the reference element. Just changing the z-index for the group focus doesn’t work since it keeps updating itself to be a very high number so changing it directly doesn’t do anything. Is there a way to prevent the group focus from updating it’s z-index? Or maybe there is another solution?