First Material data is used for Shadowmap rendering when using multiple Materials with the same Shader and different properties. This causes incorrect shadows with artifacts.

Reproduction steps:
1. Open the user's attached project and repro scene
2. In the Hierarchy window, double click TwistedTree GameObject
3. Zoom out with the mouse scroller and observe the shadow
4. Select Window/Analysis/Frame Debugger and Enable Frame debugging
5. Select UniversalRenderPipeline.RenderSingleCamera/ScriptableRenderer.Execute: Forward Renderer/MainLightShadow
6. Expand Shadows.Draw and select Draw Mesh twisted tree_leaves
7. Observe the _BaseMap Texture

Expected result: _BaseMap Texture is Tree Texture
Actual result: _BaseMap Texture is Bush Texture

Reproducible with: 7.3.1 - 7.5.2 (2019.4.16f1 - 2019.4.18f1 ), 8.2.0 - 9.0.0-preview.72 (2020.1.7f1 - 2020.1.17f1), 10.2.2 (2020.2.2f1), 11.0.0 (2021.1.0b2, 2021.2.0a2)
Not reproducible with: 7.3.1 - 7.5.2 (2019.4.0f1 - 2019.4.15f1), 8.2.0 - 9.0.0-preview.72 (2020.1.0a21 - 2020.1.6f1), 8.3.1 - 10.2.2 (2020.2.0a1 - 2020.2.1f1)
Could not test with: 2018.4.30f1, 2020.1.0a1 - 2020.1.0a20 (errors when downgrading URP)

Note: Only reproducible with custom URP shader, it is not reproducible with default URP shaders