Framebuffer blends material instead of rendering opaque

Reproduction steps:

1. Open the attached project “ReproProject“
2. In the Build Profiles, switch to Android platform
3. Build the .apk build to Quest
4. Look up and observe the result in the built Player

Expected result: The spheres should be of white color
Actual result: The spheres are of black color

Reproducible in: 2021.3.49f1, 2022.3.59f1, 6000.0.41f1, 6000.1.0b9, 6000.2.0a6

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

Reproducible with:

• Oculus Quest 2 (Quest 2), CPU: Snapdragon XR2, GPU: Adreno 650, v72, OS: 12

Notes:

• Could not test in Play Mode, due to headset not connecting to the Editor’s Play Mode
• Could not test in Windows Standalone Player, due to unsolvable errors when trying to build
• The customer noted that the issue reproduces for them when entering Play Mode via Meta Quest Link, CQA could not reproduce it there
• Though the report mentioned that the client upgraded from 2022.3.9f1, the issue is still reproducible as early as on 2022.3.5f1
• User noted: The camera's clear color appears black instead of blue due to alpha being set to 0, and the sphere objects are invisible because its material's ColorMask only writes RGB, not alpha. This suggests the framebuffer is blending when it should be opaque. A possible cause might be a bug where mixed reality mode is always enabled in XR applications, as mixed reality often uses the framebuffer's alpha for blending with real-world camera input