Shader does not use full-screen color with Single Pass Instanced Render Mode

Reproduction steps:
1. Open the attached project "ReproProj"
2. Open the “/Assets/Scenes/SampleScene.unity” Scene
3. In MockHMD settings, select Render Mode as “Single Pass Instanced” (Edit > Project Settings > MockHMD)
4. Enter the Play Mode
5. Observe the Game view

Expected result: The Scene appears the same as with “Multi Pass”
Actual result: The Scene appears grey

Reproducible with: 2023.1.0a19, 6000.0.14f1
Not reproducible with: 2021.3.42f1, 2022.3.42f1, 2023.1.0a18

Reproducible on:
Windows Platform Play Mode (VLNQA00379, Oculus (Quest 2), Android 10, CPU: Snapdragon XR2, GPU: Adreno (TM) 650)
Windows Standalone Player (VLNQA00379, Oculus (Quest 2), Android 10, CPU: Snapdragon XR2, GPU: Adreno (TM) 650)

Not reproducible on:
Android Platform Play Mode
Android Player (VLNQA00379, Oculus (Quest 2), Android 10, CPU: Snapdragon XR2, GPU: Adreno (TM) 650)

Testing environment: Windows 10 Enterprise 21H2
Not reproducible on: No other environment tested

Notes:

• Reproducible with OpenXR and Oculus XR
• Not reproducible with “Multi Pass” Rendering Mode