Purgecss + Nextjs12 + scss modules

[fraitag]

I try use purgecss with Nextjs12 with scss modules.

I have problem with configuration.

I prepared file postcss.config.js with configuration:

module.exports = {
    plugins: [
        'postcss-flexbugs-fixes',
        [
            'postcss-preset-env',
            {
                autoprefixer: {
                    flexbox: 'no-2009'
                },
                stage: 3,
                features: {
                    'custom-properties': false
                }
            }
        ],
        [
            '@fullhuman/postcss-purgecss',
            {
                content: [
                    './pages/**/*.{js,jsx,ts,tsx}',
                    './elements/**/*.{js,jsx,ts,tsx}'
                ],
                defaultExtractor: content => content.match(/[\w-/:]+(?<!:)/g) || [],
                safelist: ['html', 'body']
            }
        ]
    ]
};

And on prod build i have alert:
<w> while serializing webpack/lib/cache/PackFileCacheStrategy.PackContentItems -> webpack/lib/NormalModule -> webpack/lib/ModuleBuildError -> SassError <w> [webpack.cache.PackFileCacheStrategy] Skipped not serializable cache item 'Compilation/modules|/home/user/workspace/b-3.0/node_modules/next/dist/build/webpack/loaders/css-loader/src/index.js??ruleSet[1].rules[2].oneOf[5].use[0]!/home/user/workspace/b-3.0/node_modules/next/dist/build/webpack/loaders/postcss-loader/src/index.js??ruleSet[1].rules[2].oneOf[5].use[1]!/home/user/workspace/b-3.0/node_modules/next/dist/build/webpack/loaders/resolve-url-loader/index.js??ruleSet[1].rules[2].oneOf[5].use[2]!/home/user/workspace/b-3.0/node_modules/next/dist/compiled/sass-loader/cjs.js??ruleSet[1].rules[2].oneOf[5].use[3]!/home/user/workspace/b-3.0/elements/commons/components/ExpandButton/ExpandButton.module.scss': No serializer registered for SassError <w> while serializing webpack/lib/cache/PackFileCacheStrategy.PackContentItems -> webpack/lib/NormalModule -> webpack/lib/ModuleBuildError -> SassError info - Creating an optimized production build Failed to compile.

I found this doc https://purgecss.com/css_modules.html but I have not idea how a i can use it in Nextjs12. I have not access to webpack config file, only to object of configuration but this is not readable for human.
Anyone have ready code?