How to reproduce:
1. Open the attached “IN-131384“ project
2. In the Hierarchy window, select the “Sphere“ GameObject
3. Set the Inspector to Debug mode from the Inspector toolbar (︙ > Debug)
4. Observe the Valid Keywords field of “New Material“
5. Set the Inspector to Normal mode from the Inspector toolbar (︙ > Normal)
6. In the Inspector, set the Global Illumination of the “New Material“ to None
7. Repeat steps 3-4

Actual result: _EMISSION keyword has been removed
Expected result: _EMISSION keyword is present

Reproducible with: 6000.0.52f1, 6000.0.66f2(b20bc5da3050), 6000.3.7f1, 6000.4.0b7, 6000.5.0a6
Not reproducible with: 2023.1.0a1, 6000.0.51f1(01c3ff5872c5)

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