How to reproduce:
1. Open the user’s attached “My project (1).zip” project
2. Add “New VFX.vfx” to the Hierarchy window
3. Make a prefab from added “New VFX” GameObject
4. In the Hierarchy window, select “New VFX” GameObject
5. In the Inspector window, change the value of “A” in the “Visual Effects” component
6. Observe the result

Expected result: “A” value is changed
Actual result: “A” value hasn’t changed

Reproducible with: 2021.3.26f1, 2021.3.28f1
Not reproducible with: 2021.3.25f1, 2022.3.5f1, 2023.1.4f1, 2023.2.0a23

Reproduced on: macOS 13.4.1 (Intel)

Note: modifying the “A” value of the “New VFX” prefab selected from the Project window works