How to reproduce:
1. Open the “ReproProject.zip“ project
2. Open the “Test“ scene
3. Build and Run for Android
4. Observe the square in the middle

Expected result: The image is not clipped
Actual result: The image is clipped

Reproducible with: 2023.2.0a17, 6000.0.60f1, 6000.2.6f2, 6000.3.0b5, 6000.4.0a2

Reproducible environment: macOS 15.7 (M4 Max), Windows 11 (Reporters)
Not reproducible environment: No other environment tested

Reproducible with these devices:
VLNQA00642, Google Pixel 9a, Android 15, CPU: Google Tensor G4 (GS401), GPU: Mali-G715
VLNQA00319, Google - (Pixel 4), Android 13, CPU: Snapdragon 855 SM8150, GPU: Adreno (TM) 640
VLNQA00511, Samsung Galaxy S8 (SM-G950F), Android 9, CPU: Exynos 9 Octa 8895, GPU: Mali-G71
VLNQA00107, Huawei Nexus 6P (Nexus 6P), Android 8.1.0, CPU: Snapdragon 810 MSM8994, GPU: Adreno (TM) 430

Not reproducible with these devices:
VLNQA00491, iPhone 14 Pro (MQ083PX/A), CPU: Apple A16 Bionic, OS: 16.0

Notes:

Not reproducible in the Editor
Only reproduces with OpenGLES3, does not reproduce with Vulkan
When the width of the cut (source Rect parameter in ReadPixels) is the same as the width of Texture2D, the issue is not reproducible (If you set “Texture dimensions“ in “Test Script“ GameObject to 512x512, 512x1024, 512x2048)
If the width is set to 1024 px, we get the RenderTexture squished (the mapped image only takes up half of the Texture2D)
If the width is set to 2048 px, we get the RenderTexture squished (the mapped image only takes up 1/4 of the Texture2D)