Reproduces on master (commit (6ba6a63dd2))
Doesn't reproduce on 8.0.1 release
Repro steps:
0. Make sure the grid and gizmos are enabled
1. Use a project with Universal RP
2. Create a new scene
3. Create a plane
4. Move the plane above the grid and above the directional light
5. Look at the plane from above

Expected result: the grid is obscured and the directional light gizmo is faded out
Actual result: the grid and directional light gizmo render over the plane

Note: I've had instances where the grid and gizmos are obscured by geometry that wasn't in the location that's being obscured, but had trouble finding good repro steps for this. I assume this is the same issue.