Steps to reproduce:
1. Open the attached user's project "TestAO.zip"
2. Open the "SampleScene.unity"
3. Select "Assets/matShader.mat"
4. Switch to Game View
5. In the Inspector, change the float value of "ambient" increasingly from 0 to 20 (to any number larger than 1), you will notice that the "Cube" GameObject will stop getting affected by the value if it is larger than 1

Expected results: Ambient Occlusion with Forward Rendering Path shader does have an effect if the value is larger than 1
Actual results: Ambient Occlusion with Forward Rendering Path shader does not have an effect if the value is larger than 1

Reproducible on: URP 12.0.0 - 15.0.0 (2021.2.0b1, 2021.3.6f1, 2022.1.0b2, 2022.2.9f1, 2023.1.0a4)
Not reproducible on: URP 10.10.0 - 12.0.0 (2020.3.37f1,  2021.2.0a15)

Tested macOS 10.15 | 3,2 GHz 6-Core Intel Core i7 | Intel UHD Graphics 630 1536 MB and macOS 12.2 | 2,5 GHz Quad-Core Intel Core i7 | AMD Radeon R9 M370X 2GB
On macOS it reproduces everywhere in 2021.2.x stream
On Windows 2021.2.0a16 - 2021.2.0a21 shader no longer works and recreating it does not help (ShaderGraph throws a bunch of errors)

Notes:
-Changing the Rendering Path to Deferred will let the model get affected by values larger than 1 and this should be the case for Forward Rendering Path