With compute ray marching it means part of the shading rates logic must be done in the compute shader (in addition to it still being done in the fragment shader for the gbuffer render pass) for performance benefits in ray marching.

This means the compute shader has a shading rates buffer with the same data that is fed to the rasterization pipeline and the compute ray marching shader casts minimal rays based on said buffer.

Here's a screenshot of visually verifying the correctness of the shading rates in the compute shader: