Nx Storybook (Webpack 5) "exports is not defined" and infinite loading

I have upgraded Nx packages to latest version 14.7.5 and it broke my Storybook build which was still using Webpack 4. So I figured updating it to Webpack 5 might fix the problem and after the migration it is successfully building, but the Storybook gets stuck on the main page and infinitely shows the loading animation (XHR call /progress never returns) and in console there is Uncaught ReferenceError: exports is not defined error. This error comes from one of my generated files that is in JS (rest of the files is in TypeScript). I am not sure if the error is causing the infinite loading but it is my only clue.

When I build the Storybook statically it also shows this warning during the compilation:

 export 'AssetService' (reexported as 'AssetService') was not found in './protos/Asset_pb_service' (module has no exports)

which comes from the same file as the error in the console so it might be connected (the files has exports though).

My main Storybook configuration:

module.exports = {
  core: {
    builder: 'webpack5',
  },
  typescript: { reactDocgen: false },
  stories: [],
  addons: [
    {
      name: '@storybook/addon-essentials',
      options: {
        backgrounds: true,
        viewport: false,
      },
    },
    '@nrwl/react/plugins/storybook',
    'storybook-dark-mode'
  ],
};

Storybook configuration of the main app:

// This loads the configuration above
const rootMain = require('../../../.storybook/main');

module.exports = {
  ...rootMain,

  core: { ...rootMain.core, builder: 'webpack5' },

  stories: [
    ...rootMain.stories,
    '../src/**/*.stories.mdx',
    '../src/**/*.stories.@(js|jsx|ts|tsx)',
    '../*.stories.mdx',
    '../../../libs/**/*.stories.mdx',
    '../../../libs/**/*.stories.@(js|jsx|ts|tsx)',
  ],
  webpackFinal: async (config, { configType }) => {
    // apply any global webpack configs that might have been specified in .storybook/main.js
    if (rootMain.webpackFinal) {
      config = await rootMain.webpackFinal(config, { configType });
    }

    // add your own webpack tweaks if needed

    return config;
  },
};

Storybook package versions:

    "@storybook/addon-docs": "6.5.12",
    "@storybook/addon-essentials": "6.5.12",
    "@storybook/builder-webpack5": "6.5.12",
    "@storybook/core-server": "6.5.12",
    "@storybook/manager-webpack5": "6.5.12",
    "@storybook/react": "6.5.12",

Any help would be appreciated.