Godot version

4.0.dev (2a9dd65)

System information

Fedora 34, GeForce GTX 1080 (NVIDIA 470.74)

Issue description

When using the Vulkan Mobile backend, environment lighting and reflections appear twice as dark as they should be.

Vulkan Clustered

Vulkan Mobile

Vulkan Clustered with Ambient Light Sky Contribution set to 0.5

This makes environment lighting consistent with the mobile backend, but this doesn't adjust reflections. Since Sky Contribution can't be set above 1.0 and Energy does not affect sky contributed lighting, it's not possible to brighten ambient light on the Vulkan Mobile backend to bring it back to the level of Vulkan Clustered.

Steps to reproduce

• Add 3 MeshInstance3D nodes to the scene: 2 with the fallback material, and 1 with a fully metallic and non-rough material (to see environment reflections).
• Add a DirectionalLight3D node and a WorldEnvironment node.
• Switch to Vulkan Mobile backend in the project settings (search for back end).
  • Note: The MRP linked below already uses the Vulkan Mobile backend by default.
• Notice how environment lighting is twice as dark (but not the DirectionalLight3D itself).
• Switch back to Vulkan Clustered backend and restart the editor. Decrease Ambient Light > Sky Contribution in the WorldEnvironment to 0.5. Notice how lighting now looks very similar to the mobile backend's.

Minimal reproduction project

test_vulkan_clustered_vs_mobile_environment_lighting.zip