This is the website https://repetitionsystem.com, yes it happens when testing locally.
I’m using netlify CLI for this
$ netlify dev
Also when using the build version of the app, the react components source code is visible from the dev tools knowing that it’s not in the build directory
$ netlify build
$ serve -s build
You can view the source code by opening chrome dev tools Sources tab, on the left side navigate to top > repetitionsystem.com > static > js, there you will find the components directory along with some other configs.