How to reproduce:
1. Open the ‘ReproCase.zip' project
2. Open the 'New Scene’ scene
3. Build for iOS
4. Open the “Unity-iPhone.xcodeproj“ in Xcode
5. Build to a device
6. Open the app
7. Observe the Xcode console

Actual result: Camera background material has no _MainTex property
Expected result: Camera background material has _MainTex property

Reproducible with: 6.0.6 (6000.0.64f1(5360b7cd7953)), 6.3.1 (6000.3.1f1(37142da19a94)), 6.4.0-pre.1 (6000.4.0b1, 6000.5.0a3)

Reproducible on environment: macOS 26.0.1 (M1 Max)
Not reproducible on environment: No other environment tested

Reproducible with these devices:
VLNQA00358, iPhone 12 (MGJ93ET/A), CPU: Apple A14 Bionic, OS: 26.0.1
VLNQA00416, iPhone 13 Pro (MLVA3ET/A), CPU:  Apple A15 Bionic, OS: 17.6.1
VLNQA00632, iPhone 16e (MD1Q4QN/A), CPU: Apple A18 Pro, OS: 18.3

Could not test with these devices (Does not support 'arkit' capability):
VLNQA00543, iPad mini 4 (WiFi) (MK9N2B/A), CPU: Apple A8, OS: 15.8.3

Not reproducible with these devices:
VLNQA00612, Samsung Galaxy S24 (SM-S921B), CPU: Exynos 2400, OS: Android 15