How to reproduce:
1. Download the attached project 'CustomRenderTextureBug.zip'
2. Make sure the Graphics API in Player Settings is set to Metal
3. Build and Run on macOS (other platforms can be used too, see notes for selecting required Graphics API)

Expected result: The bottom square has red textures rendered
Actual result: The bottom square is black

Reproducible with: 2019.4.39f1, 2020.3.34f1, 2021.3.3f1, 2022.1.2f1, 2022.2.0a15

Tested with:
macOS 12.3 (Intel)
Windows 10

Reproducible on (testing with OpenGLES3):
VLNQA00001, Google Pixel 2 (Pixel 2), Android 11, CPU: Snapdragon 835 MSM8998, GPU: Adreno (TM) 540
VLNQA00225, Qualcomm null (SDM845 for arm64), Android 8.1.0, CPU: Snapdragon 845 SDM845, GPU: Adreno (TM) 630
VLNQA00316, Samsung Galaxy Note10 (SM-N970F), Android 9, CPU: Exynos 9 Series 9825, GPU: Mali-G76

Not reproducible on (testing with OpenGLES3):
VLNQA00288, Samsung Galaxy J7 (SM-J730F), Android 8.1.0, CPU: Exynos 7 Octa 7870, GPU: Mali-T830
N/A, Huawei - (NOH-NX9), Android 10, CPU: NOT FOUND, GPU: Mali-G78

Notes:
- Does not reproduce in Editor Play mode
- Does not reproduce on iOS (Metal)
- On macOS: reproduces with Metal/does not reproduce with OpenGL Core
- On Android: reproduces with OpenGLES3/does not reproduce with Vulkan
- On Windows: reproduces with OpenGL Core, OpenGLES3/does not reproduce with Vulkan, Direct3D11