Meshes become very dark when using MSAA

[jondavis847]

Hello,

I am using wgpu to render basic 3d meshes. I noticed that when I increase the sample_count from 1 to 4 for geometry multisampling, the scene becomes much darker. I'll note that I'm resolving to a texture created by the Iced crates Shader widget, but I handle all the wgpu pipeline and render pass creation. Things I've tried with no luck:

• confirmed that all pipelines, the resolve target, and the multisampling texture view all use the same format (Rgba8UnormSrgb)
• just use ambient lighting for all meshes
• change the fragment shader to just output solid colors for each mesh
• changed color target blend state to be the following

 blend: Some(wgpu::BlendState {
        color: wgpu::BlendComponent {
            src_factor: wgpu::BlendFactor::One,
            dst_factor: wgpu::BlendFactor::Zero,
            operation: wgpu::BlendOperation::Add,
        },
        alpha: wgpu::BlendComponent {
            src_factor: wgpu::BlendFactor::One,
            dst_factor: wgpu::BlendFactor::Zero,
            operation: wgpu::BlendOperation::Add,
        },
  }

This also only seems to happen when using color values < 1.0. For example, below is an image rendering a pure white cuboid in front of a pure red sphere. (4 sample_count on left, 1 sample_count on right). It looks about the same.

This is the same image but with 0.7 times the mesh color. The MSAA picture is noticeably darker.

This is with 0.3 times the mesh color:

Anything else I should be trying?