Github Workflow for Building, Releasing Flutter web app to Github Pages and Firebase Hosting

deploy.yml

# This is a basic workflow to help you get started with Actions

name: Build, Release app to Github Pages and Firebase Hosting
# name: Test, Build and Release apk
# Controls when the action will run. Triggers the workflow on push or pull request
# events but only for the master branch
on:
  push:
    branches:
      - master

# A workflow run is made up of one or more jobs that can run sequentially or in parallel
jobs:
  # This workflow contains a single job called "build"
  build:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v1
    - uses: actions/setup-java@v1
      with:
        java-version: '12.x'
    - uses: subosito/flutter-action@v1
      with:
        channel: 'dev'
    - name: 'Run flutter pub get'
      run: flutter pub get
#    - name: 'Run Test(s)'
#      run: flutter test
    - name: Enable flutter web
      run: flutter config --enable-web
    - name: 'Build Web App'
      run: flutter build web
    - name: deploy
      uses: peaceiris/actions-gh-pages@v3
      with:
        github_token: ${{ secrets.TOKEN }}
        publish_dir: ./build/web
    - name: Deploy to Firebase Hosting
      uses: w9jds/firebase-action@master
      with:
        args: deploy --only hosting
      env:
        FIREBASE_TOKEN: ${{ secrets.FIREBASE_TOKEN }}

Yes, I created the file trough VSC using firebase init hosting:github .
I uploaded it manually into the main branche and it is not in gitignore and it is being tracked.
These are the contents of my firebase.json , same as yours.

{
  "hosting": {
    "public": "build/web",
    "ignore": [
      "firebase.json",
      "**/.*",
      "**/node_modules/**"
    ],
    "rewrites": [
      {
        "source": "**",
        "destination": "/index.html"
      }
    ]
  }
}

I was able to fix the issue by adding this deployment script instead of the other one:

  deploy:
    name: Deploy
    needs: build
    runs-on: ubuntu-latest
    steps:
      - name: Checkout Repo
        uses: actions/checkout@master
      - name: Download Artifact
        uses: actions/download-artifact@master
        with:
          name: web-build
          path: build/web
      - name: Deploy to Firebase
        uses: w9jds/firebase-action@master
        with:
          args: deploy --only hosting
        env:
          GCP_SA_KEY: ${{ secrets.FIREBASE_SERVICE_ACCOUNT_PAPERWIZ1 }}

I actually believe this made the difference:

        uses: actions/download-artifact@master
        with:
          name: web-build
          path: build/web

It was uploading the artifacts but not downloading them for deployment.