### Godot version

4.1.1

### System information

windows 11, mobile renderer

### Issue description

On Mobile Vulkan renderer, the clear color is 50% lighter than expected

See steps to reproduce and Minimal reproduction project below.

The box and background have the same color on Forward+ and compatibility, but not on Mobile
happens also in runtime on exported project, not only in editor preview

Images of the same scene from
compatibility:
![compatibility](https://github.com/godotengine/godot/assets/11915378/a874fa86-c16f-43ef-aed7-c2066b770ac1)
Forward+:
![forward](https://github.com/godotengine/godot/assets/11915378/e416f9a6-dfd4-4c47-bbc2-b552ca58f83c)
Mobile:
![mobile](https://github.com/godotengine/godot/assets/11915378/e28e2db8-f7c3-47e2-8c0a-44ce937c9270)


### Steps to reproduce

 - add a CSGBox3D with "unshaded" shading, and albedo of #545454
 - add environment with Background = Custom color and color of #545454

Box and background are not the same color

### Minimal reproduction project

[bg_color.zip](https://github.com/godotengine/godot/files/12174822/bg_color.zip)

Vector<RID> fb;
	fb.push_back(p_color); 
	fb.push_back(p_depth); 
	
	Vector<RD::FramebufferPass> passes;
	RD::FramebufferPass pass;
	
	pass.color_attachments.push_back(0);
	pass.depth_attachment = 1;
	
	passes.push_back(pass);
	
	passes.push_back(pass);
	
	passes.push_back(pass);
	return RD::get_singleton()->framebuffer_create_multipass(fb, passes);
}
void RenderForwardMobile::setup_render_buffer_data(Ref<RenderSceneBuffersRD> p_render_buffers) {
	Ref<RenderBufferDataForwardMobile> data;
	data.instantiate();
	p_render_buffers->set_custom_data(RB_SCOPE_MOBILE, data);
}
bool RenderForwardMobile::free(RID p_rid) {
	if (RendererSceneRenderRD::free(p_rid)) {
		return true;
	}
	return false;
}
float RenderForwardMobile::_render_buffers_get_luminance_multiplier() {