BaseShaderGUI.Styles is inaccessible to subclasses, causing compilation errors when overriding DrawSurfaceOptions

Steps to reproduce:
1. Create new Unity project using Universal 3D Template
2. Import the provided script “QACustomShaderGUI.cs” into the project
3. Observe the Console window

Actual results: The script fails to compile and the following errors are thrown in the Console window:

Assets/QACustomShaderGUI.cs(8,17): error CS0122: 'BaseShaderGUI.Styles' is inaccessible due to its protection level                 
Assets/QACustomShaderGUI.cs(9,17): error CS0122: 'BaseShaderGUI.Styles' is inaccessible due to its protection level

Expected results: The script compiles without errors, as BaseShaderGUI.Styles should be accessible to subclasses extending BaseShaderGUI

Reproducible with versions: 6000.7.0a4 (7305b6f6fd4f), 6000.7.0b2, 7000.0.0a1

Not reproducible with versions: 6000.6.3f1. 6000.7.0a3 (4e1564fc2cca)

Tested on (OS): Windows 11