Repro steps:
1. Import the attached package and open SortingScene
2. Make sure both the game and scene view are visible
3. Pan around the effect in the scene view and observe the flickering (usually, looking at the effect straight-on in the scene view causes larger flickering)
4. Move either the effect or the camera on the Y axis.
5. Observe the large flickering stops

Expected outcome: no severe flickering

Notes:
- the scene view position is important; looks like sorting clashes between game and scene view
- looks related to https://fogbugz.unity3d.com/f/cases/1203011/, the count does matter, but this issue has the additional element of a more severe flickering and the camera position.
- feels like a regression, but would need more investigating, so not setting it as one unless we find evidence to the contrary.