Firebase deployed react app not working. Uncaught SyntaxError: Unexpected token '<'

I have my app perfectly running in http://localhost:3000/ when I run my development server with npm start. However, when I npm run build and the firebase deploy the app, the app is not running and is throwing the error: Uncaught SyntaxError: Unexpected token '<'.

Find my firebase.json:

{
  "functions": {
    "predeploy": [
      "npm --prefix \"$RESOURCE_DIR\" run lint"
    ]
  },
  "hosting": {
    "public": "build",
    "ignore": [
      "firebase.json",
      "**/.*",
      "**/node_modules/**"
    ],
    "rewrites": [
      {
        "source": "**",
        "destination": "/index.html"
      }
    ]
  }
}

I tried to add this, in case something was catched with no success:

"headers": [
      {
        "source" : "/sw.js",
        "headers" : [
          {
            "key" : "Cache-Control",
            "value" : "no-store"
          }
        ]
      }
    ]

And my package.json:

{
  "name": "marioplan",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "@testing-library/jest-dom": "^5.11.6",
    "@testing-library/react": "^11.2.2",
    "@testing-library/user-event": "^12.6.0",
    "firebase": "^8.2.1",
    "moment": "^2.29.1",
    "react": "^17.0.1",
    "react-dom": "^17.0.1",
    "react-redux": "^7.2.2",
    "react-redux-firebase": "^3.0.0",
    "react-router-dom": "^5.2.0",
    "react-scripts": "4.0.1",
    "redux": "^4.0.5",
    "redux-firestore": "^0.14.0",
    "redux-thunk": "^2.3.0",
    "web-vitals": "^0.2.4"
  },
  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "react-scripts test",
    "eject": "react-scripts eject"
  },
  "eslintConfig": {
    "extends": [
      "react-app",
      "react-app/jest"
    ]
  },
  "browserslist": {
    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ]
  }
}

I read somthing and made trials regarding '"homepage":' needed to be specified in the packaje.jason, as the npm run build throws:

The project was built assuming it is hosted at /. You can control this with the homepage field in your package.json.

Also I tried removing npm --prefix \"$RESOURCE_DIR\" run lint predeploy command as I am not clear about what it does also with no different results.

Just in case anyone might wonder, I do check that the files are actually deployed in the firebase hosting console.