Loss of precision after converting model coordinates to world coordinates

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Cesium Sandcastle

In this example, using CustomShader to convert model coordinates to world coordinates, and then converting world coordinates to model coordinates, but the coordinates lose precision.

const modelShader = new Cesium.CustomShader({
  vertexShaderText: `
    void vertexMain(VertexInput vsInput, inout czm_modelVertexOutput vsOutput)
    {
      vec4 positionWC = czm_model * vec4(vsInput.attributes.positionMC, 1.0);
      vsOutput.positionMC = (czm_inverseModel * positionWC).xyz;
    }
    `,
});

I want to convert the model coordinates to world coordinates for some operations, and then convert them back. Is there any good way?