How to reproduce:
1. Open the “TestFullScreenShader“ project
2. Open the “SampleScene Failed“ scene
3. Observe the top-right and bottom-right corners of the Game view

Expected result: Black areas appear
Actual result: No black areas

Reproducible with: 6000.1.0a1, 6000.0.24f1
Could not test with: 2021.3.45f1, 2022.3.51f1 (The custom render features cannot be applied)

Reproducible on: macOS 14.6.1 (Intel), Windows 10 (Reporters)
Not reproducible on: No other environments tested

Workaround 1: Clamp the URP Sample Buffer Node input Max (X and Y values) to 0.999

Workaround 2: Instead of the URP Sample Buffer use the Sampler State Node and Sample Texture 2D Node

Note: To see the second workaround navigate to the “SampleScene.unity“ which uses “Twirl Shader Graph“