Reproduction steps:
1. Open the user's attached project
2. Load the "PortalVRBug" scene
3. Enter play mode
4. Change the Game view to show both eyes
5. Select the Main Camera GameObject in the Hierarchy (CameraRig > Main Camera)
6. Toggle the Post-process Layer Component in the Inspector window on and off
Expected result: the right eye's view does not change
Actual result: the right eye's view is shifted
Reproducible with: Post Processing 3.1.1 (2019.4.29f1, 2020.3.16f1, 2021.1.17f1, 2021.2.0b6, 2022.1.0a5)
Note: the issue does not occur with Single Pass Instanced Rendering mode.