Reproduction steps:
1. Open the attached “TerrainPainting.zip“ project
2. Open the “Test World 2” Scene (Assets > Nature > Scenes)
3. Double click on the “PROBLEM EXAMPLE” GameObject from the Hierarchy
4. Observe the Detail Mesh in that spot in the Scene view

Expected result: All of the grass Detail Meshes are green and look the same
Actual result: One grass Detail Mesh appears black

Reproducible with: 2022.3.39f1, 6000.0.12f1
Couldn’t test with: 2021.3.41f1 (All of the grass was black)

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

Notes:
- Reproducible when adding new Detail Mesh around every 5-6th time using the Brush
- Brushing over that spot again fixes the Mesh color
- Issue seems to mostly reproduce when using Brush Size with a value around 8 and bigger. Painting with a smaller value usually results in showing the black Detail Mesh only for a frame and then fixing it itself