Why doesn't the plugin change class names in WordPress php files?

Question

PHP

I'm trying to obfuscate (encrypt/reduce) class names in a WordPress template.
Through webpack, I connected the plugin for obfuscation mangle-css-class-webpack-plugin and when the command is run, the whole process passes without error and the classes from the css file are reduced, but there are no classes from the php files.

configuration file

webpack.config.js

const webpack = require('webpack');
const path = require('path');
const HtmlWebpackPlugin = require('html-webpack-plugin');
const MangleCssClassPlugin = require('mangle-css-class-webpack-plugin');
const MiniCssExtractPlugin = require('mini-css-extract-plugin');

module.exports = {
  mode: 'development',
  entry: [
        './src/index.js',
        './index.php'
    ],
    output: {
        path: path.resolve(__dirname, './dist'),
        filename: '[name].js'
    },
    module: {
    rules: [
            { test: /\.js$/, loader: 'babel-loader', exclude: /node_modules/ },
            { test: /\.css$/i, use: [ MiniCssExtractPlugin.loader, { loader: 'css-loader', options: { importLoaders: 1, modules: false } }, { loader: 'postcss-loader' } ] },
            {
                test: /\.php$/,
                use: [
                    {
                        loader: 'file-loader',
                        options: {
                            name: '[path][name].[ext]',
                            outputPath: '/'
                        }
                    }
                ]
            },
        ]
  },
    plugins: [
        new CleanWebpackPlugin(),
        new MiniCssExtractPlugin({
            filename: "assets/css/main.css"
        }),
        new MangleCssClassPlugin({
            classNameRegExp: '((hover|focus|active|disabled|visited|first|last|odd|even|group-hover|focus-within|xs|sm|md|lg|xl)[\\\\]*:)*tw-[a-zA-Z0-9_-]*([\\\\]*\/[0-9]*)?',
            ignorePrefixRegExp: '((hover|focus|active|disabled|visited|first|last|odd|even|group-hover|focus-within|xs|sm|md||lg|xl)[\\\\]*:)*',
            reserveClassName: ['fa', 'fas', 'far'],
            log: true
        })
    ],
};

The feeling that Webpack does not scan classes from php files in any way, or I'm most likely doing something wrong.