How to reproduce:
1. Open the attached “IN-134119_ViewportBug” project
2. Open the “SampleScene” Scene
3. Navigate to Assets → Settings → PC_RPAsset
4. In the Inspector window make sure that the Quality → Upscaling Filter is set to either “Automatic” or “Bilinear”
5. Observe the Game view

Actual result: “Main Camera_Right” renders a dark blue background
Expected result: “Main Camera_Right” renders a glowing cube and a blue rectangle

Reproducible with: 2023.3.0b6, 6000.0.67f1, 6000.3.8f1, 6000.4.0b8, 6000.5.0a6
Not reproducible with: 2023.2.0a23
Could not test with: 2023.3.0a2, 2023.3.0b5 (The Editor threw errors and nothing was Rendered in Game view)

Reproducible on: Windows 11
Not reproducible on: No other environments tested

Notes:
- In Unity versions 6000.4.0b8 and 6000.5.0a6, the issue also reproduces when the Upscaling Filter is set to “Nearest-Neighbor” or “Spatial-Temporal Post-Processing”
- In Unity version 2023.3.0a2, “RenderPass”, “BeginSubPass” and “EndRenderPass” errors are thrown, and no camera is being rendered correctly regardless of which mode the Upscaling Filter is set to
- In Unity version 2023.3.0b5 nothing was rendered in Game View
- In Unity version 2023.3.0b6, “Main Camera_Right” renders a black background and a blue rectangle when the Upscaling Filter is set to either “Automatic” or “Bilinear” or "Nearest Neighbor" and renders just a black background when the Upscaling Filter is set to "FidelityFX Super Resolution 1.0"