Liberary dotenv-webpack doesn't work with vue 3 and webpack-cli

I'm using Vue 3 and Webpack 5 and wanted to install dotenv-webpack, but I can't get it to work.
Here's full code: https://github.com/golebiewska-n/webpack5-vue3

Setup:
package.json script I'm using to launch the app

webpack-cli serve

webpack.config.js

const Dotenv = require('dotenv-webpack')
...
module.exports = (env) => {
  return {
    ...
    plugins: [
       ...
       new Dotenv()
    ]
  }
}

.env (added in the root folder of my app)

VUE_APP_VAR=123

main.js

console.log(process.env)

and output in console is: "MISSING_ENV_VAR"

I tried removing new webpack.DefinePlugin({...}) from plugins in webpack config, but it didn't help.