upstairs is wrong, you can look here.
here is an example of getting started with webpack4. You can take a look at https://github.com/crlang/eas..

Let's talk about my problem first. Here is my directory structure (the following files / folders named with test are used for this test)

webpack

sass

src/img/test/test.pngdist/img/test/test.png

dist/imgcssdist/css/img

src
publicPath

,publicPathcsspublicPathpublicPathname

dist/imgfileurl

emm,dist/imgQAQfileurlnameQAQ/test.png

namefile'QAQ/',publicPathurl

you can see that this has achieved the desired effect, and the image reference path in the packaged css is fine.
I hope this will provide some help to the landlord. In addition, if there are any mistakes, please point out that, after all, the language of writing something for the first time is a bit confusing (lying down)

build==>utils.js:
if (options.extract) {
      return ExtractTextPlugin.extract({
        use: loaders,
        fallback: 'vue-style-loader',
        publicPath:'../../'  //
      })
    } else {
      return ['vue-style-loader'].concat(loaders)
    }
    
 cssjsconfig==>index.js:
build: {
    env: require('./prod.env'),
    index: path.resolve(__dirname, '../dist/index.html'),
    assetsRoot: path.resolve(__dirname, '../dist'),
    assetsSubDirectory: 'static',
    assetsPublicPath: './',  //'/''./'
    productionSourceMap: false,
    ...
   }