uninstall Purgecss and Laravel Mix code example
Example: laravel mix purge css
npm install laravel-mix-purgecss --save-dev
const mix = require('laravel-mix');
require('laravel-mix-purgecss');
// ...
mix.js('resources/js/app.js', 'public/js')
.sass('resources/sass/app.scss', 'public/css')
.purgeCss(); //Add this line and that'll do the job