What environment variables are you using with Volto? In this configuration you should set RAZZLE_INTERNAL_API_PATH to http://192.168.141.130:8080/Plone (so the Volto server can access the backend directly) but you should not set RAZZLE_API_PATH (so the Volto client in the browser accesses /++api++ at the same hostname, to avoid CORS)
GET http://192.168.141.130:3001/static/js/runtime~client.js net::ERR_CONNECTION_REFUSED
192.168.141.130/:6
GET http://192.168.141.130:3001/static/js/client.js net::ERR_CONNECTION_REFUSED
Are you starting Volto with make frontend-start? That runs Volto in development mode, where it watches for changes in files and shows updates immediately. That requires a separate websocket server which is on port 3001. You haven't exposed that through nginx, so that's why the CSS can't be loaded.
To start in production mode, you can run pnpm start:prod in the frontend folder. (The cookieplone templates don't include a make command for this, since they promote Docker as the preferred way to deploy Plone.)