一开始的时候用的是autoprefixer，无效，后来换成postcss-preset-env还是无效。重点是还不报错，看了文档，还是没有找到解决方案，烦请老师解惑。
node版本：v13.14.0
npm版本：6.14.4

webpack.config.js

const path = require('path')
module.exports = {
  mode: 'development', 
  entry: {
    main: './src/index.js'
  },
  module: {
    rules: [{
      test: /\.(jpg|png|gif)$/,
      use: {
        loader: 'url-loader',
        options: {
          name: '[name]_[hash].[ext]',
          outputPath: 'images/',
          limit: 2048
        }
      }
    }, {
      test: /\.less$/,
      use: [
        'style-loader',
        'css-loader',
        'less-loader',
        {
          loader: "postcss-loader",
          options: {
            postcssOptions: {
              plugins: [
                ['postcss-preset-env']
              ]
            }
          }
        }
      ]
    }]
  },
  //出口配置
  output: {
    filename: 'bundle.js',
    //__dirname 当前文件所在的绝对路径
    path: path.resolve(__dirname, 'dist')
  }
}

package.json

{
  "name": "webpack5",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "build": "webpack"
  },
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "css-loader": "^5.2.6",
    "file-loader": "^6.2.0",
    "less": "^4.1.1",
    "less-loader": "^10.0.1",
    "postcss": "^8.3.5",
    "postcss-loader": "^6.1.1",
    "postcss-preset-env": "^6.7.0",
    "style-loader": "^2.0.0",
    "url-loader": "^4.1.1",
    "webpack": "^5.43.0",
    "webpack-cli": "^4.7.2"
  },
  "dependencies": {},
  "browserslist": [
    "> 1%",
    "last 2 versions",
    "not ie <= 8"
  ]
}