Do ES6 modules slow down website loading speed?

Question

JavaScript

If I use ES6 modules when developing with webpack, then everything is clear. Webpack collects all modules into one bundle, which is loaded onto the page with one request. If you use modules in the browser, then do I understand correctly that the modules will be loaded dynamically, thereby repeatedly (if there are many modules) increasing the number of requests to the server and thereby reducing the site loading speed?