How to grant DevOps pipeline access to app service API

In my pipeline file, after I deploy to an app service slot (which has network restrictions enabled), I want to execute an API on the app service, but keep getting 403 - Forbidden.

Here is my powershell task:

- stage: Deploy
  jobs:
  - deployment:
    pool:
      vmImage: 'windows-latest'
    strategy:
      runOnce:
        deploy:
          steps:
          - task: PowerShell@2
            condition: eq(variables.deployToSlot, 'true')
            inputs:
              targetType: 'inline'
              script: |
                $repoUrl = "https://$(azureWebAppName)-staging.azurewebsites.net/api/warmup"
                Invoke-RestMethod -Uri $repoUrl -Method "GET" -ContentType "application/json; charset=utf-8"

I added AzureDevOps service tag as inbound rule under network settings on the app service slot, thinking this would allow the API call from the pipeline to succeed:

Here is the result:

Error 403 - Forbidden
The web app you have attempted to reach has blocked your access.