Pass multiline string of actions' script output as input to other action in GitHub Actions

I am building a multiline string of an image to be pushed to multiple registries using the docker build/push action. I use the actions' script.

      - uses: actions/github-script@v6
        id: set-images
        with:
          script: |
            let imageList = '';
            let Base = '${{ env.REPOSITORY }}'+'/'+'${{ env.GCR_PROJECT }}'+'/'+'${{ inputs.image_name }}'
            if (${{ inputs.image_build }}) {
            imageList += (Base+':${{ inputs.image_tag }}\n');
            }
            if (${{ inputs.image_tag_stable }}) {
            imageList += (Base+':stable\n');
            }
           .
           .
           .

          return imageList.trim()

and the build:

      - name: build and push images
        uses: docker/build-push-action@v3
        with:
          push: true
          context: ${{ inputs.context }}
          build-args: ${{ inputs.build_args }}
          tags: ${{ steps.set-images.outputs.result }}

However the last one fails due to the \n being literally interpreted by the tags input

invalid tag "gcr.io/my-gcr-project/my-image:my-tag\\ngcr.io/my-gcr-project/my-tag:latest\\n": invalid reference format

Any way around this?