Sometimes Google Chrome isn’t your default browser for surfing the internet, but it is your default browser during development. With create-react-app you can specify an alternate browser to automatically open (or no browser at all), to avoid opening the wrong development browser all the time.
Just pre-pend the browser to the start script:
{
"name": "custom-browser",
"version": "0.1.0",
...
"scripts": {
"start": "BROWSER='Google Chrome' react-scripts start",
...
}
}