GENERATE_SOURCEMAP=false Issue

Another solution is to create a new file in your project's root directory named .env and include the following inside the file. This will remove any .map files from your build/static/js folder the next time you run build.

GENERATE_SOURCEMAP=false

You can find more info about source maps here.

Keep this in package.json:

"build": "GENERATE_SOURCEMAP=false react-scripts build",
"winBuild": "set \"GENERATE_SOURCEMAP=false\" && react-scripts build",

Use npm run build for creating build on Linux.

Use npm run winBuild for creating build on Windows.

Also you can try the below setting in your scripts if you are running on windows

"build": "set \"GENERATE_SOURCEMAP=false\" && react-scripts build"