(Built-In) Custom Editor GUI for a ShaderGraph is not used when the GUI name starts with any letter after U

Unity: ShaderGraph

2023.3.X

2022.3.X

2021.3.X

2023.2.X

This fix will be available in 23.3.

Reproduction steps:
1. Open the “ShaderCustomEditor“ project
2. Select the “MyMaterial“ asset and observe the Inspector

Expected result: “Hello World!“ is visible
Actual result: “Hello World!” is not visible meaning the specified Custom Editor GUI is not used

Reproduced in: 2021.3.7f1, 2022.3.7f1, 2023.1.8f1, 2023.2.0b4
Not reproduced in: 2021.3.8f1, 2021.3.29f1

Reproduced using: macOS 13.4.1 (Intel), macOS 13.5 (M2)

Workaround: Rename the custom Editor GUI script and its class to start with U (Unity) or any prior letter