You don't actually have to worry about deprecation warnings, from time to time some or the other library will adapt to something new and deprecate the previous (it will work fine though) for various reasons like security loopholes, performance or something better. Your warning appears to be related to html-webpack-plugin

In your webpack.config add the stats property like below to suppress warnings

module.exports = {
  entry: './index.js',
  stats: { warnings:false }
}

Also, try uninstalling your html-webpack-plugin and install latest || upgrade to fix it

node --trace-deprecation ./node_modules/.bin/the_library_name_here will list all deprecations

You could do npm outdated to check the latest versions. or simply npm update --force as well to update.