Reproduction steps:
1. Open the attached “IN-96360 Terrain Details Tool Bug (3D HDRP).zip“ project (link in the internal comments)
2. Open the “ForUnityBugs“ scene from the “Assets” folder in the Project window
3. Observe the Game view

Expected result: All of the foliage (ferns) are the same green colour
Actual result: Some of the foliage (ferns) are either darker or brighter than the rest

Reproducible with: 6000.0.45f1, 6000.1.0b13, 6000.2.0a8
Could not test with: 2021.3.50f1, 2022.3.60f1 (shader errors after downgrading - the scene appears blank)

Reproduced on: Windows 11 Pro (23H2 and 24H2)
Not reproduced on: No other environment tested

Workaround:
1. Go to Edit > Project Settings… > Graphics
2. Open the HDRP tab in the “Pipeline Specific Settings” section
3. Scroll down to the “Frame Settings (Default Values)” section
4. Expand the “Lighting” category
5. Disable the “Light Layers” property

Notes:
- Could not reproduce in a new project with the same assets (got the expected result)
- Could not test in Player due to compilation errors (the provided project is just a part of the user’s original project and, therefore, has compilation errors that cannot be fixed)
- The user provided information that the issue is reproducible in Editor, Play mode and Player
- Could not test with URP (the provided project is using HDRP and is too complex to change the SRP without causing additional issues)
- The issue seems like a probe leaking issue, but disabling the “Reflection Probe” GameObject does not resolve the issue
- Disabling the “Global Volume” GameObject does not resolve the issue either
- The issue does not reproduce on prefabs placed independently (when not using the Paint Details Terrain tool)