istanbul get wrong coverage for svelte file

I am trying to get e2e test using playwright, and hope to get coverage using istanbul. The coverage report show the wrong coverage,and it not change when running extra test file.

window.__coverage__ in the console seems to show that the report is from code compiled from the svelte component.

I am wondering

why the coverage remains the same？

is it because the loader does not support sourcemap or is there something wrong with my config this is my config

// webpack loader config
{
    test: /\.svelte$/,
    include: [
      path.resolve(__dirname, 'src'),
      path.resolve(__dirname, 'node_modules/svelte-routing')
    ],
    use: [
      'babel-loader',
      {
        loader: 'svelte-loader',
        options: {
          emitCss: true,
          hotReload: !prod,
          hotOptions: {
            noPreserveState: false,
            optimistic: true
          },
          compilerOptions: {
            dev: !prod,
            css: false
          },
          preprocess: SveltePreprocess({
            sourceMap: true,
            scss: true,
            sass: true,
            postcss: {
              plugins: [Autoprefixer],
              'postcss-preset-env': true
            }
          })
        }
      }
    ]
  }

// babel config
module.exports = {
  presets: ['@babel/preset-env', '@babel/preset-typescript'],
  plugins: [
    [
      '@babel/plugin-transform-runtime',
      {
        corejs: 3,
        useESModules: true,
        version: '^7.18.3'
      }
    ]
  ],
  env: {
    development: {
      plugins: [
        [
          'istanbul',
          {
            exclude: ['**/tests/*.spec.ts', '**/src/components/index.ts'],
            // include: ['**/src/**/*.(ts|svelte)'],
            extension: ['.ts', '.svelte'],
            useInlineSourceMaps: false
          }
        ]
      ]
    }
  }
};

sveltejs / svelte-loader

istanbul get wrong coverage for svelte file #210