Object | FunctionModern.js integrates PostCSS by default, you can configure postcss-loader through tools.postcss.
It should be noted that when you enable the tools.lightningcss configuration, PostCSS will be disabled by default, including postcss-loader and its default plugins.
The usage of this configuration item is exactly the same as that of Rsbuild. For detailed information, please refer to Rsbuild - tools.postcss.