How to correctly push a Docker image using Github actions

I am setting up a Github action to push a Docker image to Docker Hub following Github official README.md for docker/build-push-action@v2.

This is my action inside directory .github/workflows/

name: Publish Docker image

on:
  push:
    branches: master

jobs:
  push_to_registry:
    name: Push Docker image to Docker Hub
    runs-on: ubuntu-latest
    steps:
      -
        name: Set up QEMU
        uses: docker/setup-qemu-action@v1
      -
        name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v1
      -
        name: Login to DockerHub
        uses: docker/login-action@v1
        with:
          username: ${{ secrets.DOCKER_USERNAME }}
          password: ${{ secrets.DOCKER_PASSWORD }}
      -
        name: Build and push
        id: docker_build
        uses: docker/build-push-action@v2
        with:
          push: true
          tags: user/app:latest
      -
        name: Image digest
        run: echo ${{ steps.docker_build.outputs.digest }}

Having tested the action worked in my fork branch I then merged the branch to the main repo. To my surprise the login step failed showing the following error inside Github actions log

Run docker/login-action@v1
  with:
    logout: true
Error: Username and password required

At first I thought I could have wrongly defined (or even not defined) the secrets inside the main repo but after a request with octokit I found out that they are there

{
  total_count: 2,
  secrets: [
    {
      name: 'DOCKER_PASSWORD',
      created_at: '2020-11-04T15:28:55Z',
      updated_at: '2020-11-16T13:11:27Z'
    },
    {
      name: 'DOCKER_USERNAME',
      created_at: '2020-11-04T15:28:55Z',
      updated_at: '2020-11-16T13:11:27Z'
    }
  ]
}

I guess that docker/login-action@v1 is not using username and password provided after the with: keyword. I am very puzzled by this as it did work on my fork branch and do not understand why with: is sending the keyword logout: true instead which I did not set.

Does someone have more insight into this ?