As @Thomas Delrue pointed out, the issue was caused by using an emptyDir volume. However, instead of switching to a PersistentVolume (PV), I initially intended to use artifacts .

Here's my updated Argo Workflow file:

apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: build-image
  namespace: argo-workflows
spec:
  serviceAccountName: argo-workflow
  entrypoint: build-and-deploy-env
  arguments:
    parameters:
      - name: env_name
        value: test
      - name: aws_region
        value: eu-west-1
      - name: expiration_date
        value: "2024-12-31T23:59:59Z"
      - name: values_path
        value: ./demo-app/helm/values.yaml
      - name: configurations
      - name: configurations
        value: '[{"keyPath": "global.app.main.name", "value": "updated-app"}, {"keyPath": "global.service.backend.port", "value": 8080}]'
      - name: application_list
        value: '[{"name": "backend", "repo_url": "org/project-demo-app.git", "branch": "demo-app", "ecr_repo": "demo-app/backend", "path_inside_repo": "backend"}, {"name": "frontend", "repo_url": "org/project-demo-app.git", "branch": "demo-app", "ecr_repo": "demo-app/frontend", "path_inside_repo": "frontend"}]'

  templates:
    - name: build-and-deploy-env
      dag:
        tasks:
          - name: build-push-app
            template: build-push-template
            arguments:
              parameters:
                - name: app
                  value: "{{item}}"
            withParam: "{{workflow.parameters.application_list}}"

    - name: build-push-template
      inputs:
        parameters:
          - name: app
      dag:
        tasks:
          - name: clone-and-check
            template: clone-and-check-template
            arguments:
              parameters:
                - name: app
                  value: "{{inputs.parameters.app}}"

          - name: build-and-push
            template: kaniko-build-template
            arguments:
              parameters:
                - name: name
                  value: "{{tasks.clone-and-check.outputs.parameters.name}}"
                - name: image_tag
                  value: "{{tasks.clone-and-check.outputs.parameters.image_tag}}"
                - name: ecr_url
                  value: "{{tasks.clone-and-check.outputs.parameters.ecr_url}}"
                - name: ecr_repo
                  value: "{{tasks.clone-and-check.outputs.parameters.ecr_repo}}"
              artifacts:
                - name: source-code
                  from: "{{tasks.clone-and-check.outputs.artifacts.source-code}}"
            when: "{{tasks.clone-and-check.outputs.parameters.build_needed}} == true"
            dependencies: [clone-and-check]

          - name: debug-list-files
            template: debug-list-files
            arguments:
              parameters:
                - name: name
                  value: "{{tasks.clone-and-check.outputs.parameters.name}}"
              artifacts:
                - name: source-code
                  from: "{{tasks.clone-and-check.outputs.artifacts.source-code}}"
            dependencies: [clone-and-check]

    - name: clone-and-check-template
      inputs:
        parameters:
          - name: app
      outputs:
        parameters:
          - name: name
            valueFrom:
              path: /tmp/name
          - name: image_tag
            valueFrom:
              path: /tmp/image_tag
          - name: ecr_url
            valueFrom:
              path: /tmp/ecr_url
          - name: ecr_repo
            valueFrom:
              path: /tmp/ecr_repo
          - name: path_inside_repo
            valueFrom:
              path: /tmp/path_inside_repo
          - name: build_needed
            valueFrom:
              path: /tmp/build_needed
        artifacts:
          - name: source-code
            path: /workspace/source
      container:
        image: bitnami/git:latest
        command: [bash, -c]
        args:
          - |
            set -e
            apt-get update && apt-get install -y jq awscli

            APP=$(echo '{{inputs.parameters.app}}' | jq -r '.name')
            REPO_URL=$(echo '{{inputs.parameters.app}}' | jq -r '.repo_url')
            BRANCH=$(echo '{{inputs.parameters.app}}' | jq -r '.branch')
            ECR_REPO=$(echo '{{inputs.parameters.app}}' | jq -r '.ecr_repo')
            PATH_INSIDE_REPO=$(echo '{{inputs.parameters.app}}' | jq -r '.path_inside_repo')

            # Clone to the artifact path
            git clone --branch $BRANCH https://x-access-token:[email protected]/$REPO_URL /workspace/source
            cd /workspace/source/$PATH_INSIDE_REPO
            
            if [[ ! -f "Dockerfile" ]]; then
              echo "Dockerfile not found in $PATH_INSIDE_REPO"
              exit 1
            fi

            COMMIT_HASH=$(git rev-parse --short HEAD)
            IMAGE_TAG="${APP}-${BRANCH}-${COMMIT_HASH}-{{workflow.parameters.env_name}}"

            ECR_URL="$AWS_ACCOUNT_ID.dkr.ecr.{{workflow.parameters.aws_region}}.amazonaws.com"
            EXISTS=$(aws ecr describe-images --repository-name $ECR_REPO --image-ids imageTag=$IMAGE_TAG 2>/dev/null || echo "not-found")

            if [[ "$EXISTS" != "not-found" ]]; then
              echo "false" > /tmp/build_needed
            else
              echo "true" > /tmp/build_needed
            fi

            echo "$APP" > /tmp/name
            echo "$IMAGE_TAG" > /tmp/image_tag
            echo "$ECR_URL" > /tmp/ecr_url
            echo "$ECR_REPO" > /tmp/ecr_repo
            echo "$PATH_INSIDE_REPO" > /tmp/path_inside_repo
            
        env:
          - name: ALL_REPO_ORG_ACCESS
            valueFrom:
              secretKeyRef:
                name: github-creds
                key: ALL_REPO_ORG_ACCESS
          - name: AWS_ACCOUNT_ID
            valueFrom:
              secretKeyRef:
                name: registry-creds
                key: AWS_ACCOUNT_ID
          - name: AWS_REGION
            value: "{{workflow.parameters.aws_region}}"

    - name: debug-list-files
      inputs:
        parameters:
          - name: name
        artifacts:
          - name: source-code
            path: /workspace/source
      container:
        image: alpine:latest
        command: [sh, -c]
        args:
          - |
            echo "=== Listing /workspace/source ==="
            ls -la /workspace/source
            echo "=== Listing application directory ==="
            ls -la /workspace/source/*/
            echo "=== Finding Dockerfiles ==="
            find /workspace/source -name "Dockerfile" -type f

    - name: kaniko-build-template
      inputs:
        parameters:
          - name: name
          - name: image_tag
          - name: ecr_url
          - name: ecr_repo
        artifacts:
          - name: source-code
            path: /workspace/source
      container:
        image: gcr.io/kaniko-project/executor:latest
        command:
          - /kaniko/executor
        args:
          - --context=dir:///workspace/source/{{inputs.parameters.name}}
          - --dockerfile=Dockerfile
          - --destination={{inputs.parameters.ecr_url}}/{{inputs.parameters.ecr_repo}}:{{inputs.parameters.image_tag}}
          - --cache=true
          - --verbosity=debug
        env:
          - name: AWS_REGION
            value: "{{workflow.parameters.aws_region}}"
          - name: AWS_ACCESS_KEY_ID
            valueFrom:
              secretKeyRef:
                name: registry-creds
                key: AWS_ACCESS_KEY_ID
          - name: AWS_SECRET_ACCESS_KEY
            valueFrom:
              secretKeyRef:
                name: registry-creds
                key: AWS_SECRET_ACCESS_KEY
          - name: AWS_SESSION_TOKEN
            valueFrom:
              secretKeyRef:
                name: registry-creds
                key: AWS_SESSION_TOKEN
          - name: AWS_SDK_LOAD_CONFIG
            value: "true"