This feature is about Jenkins tfs-plugin polling Azure DevOps for new PRs using Azure DevOps API rather than polling Git. Similar functionality is currently offered by the Stash Pullrequest Builder Jenkins plugin (see https://plugins.jenkins.io/stash-pullrequest-builder/).
The rationale is to avoid exposing Jenkins to the Internet (see https://stackoverflow.com/questions/54810668/azure-devops-pull-request-and-jenkins-behind-corporate-network; using hooks on Azure DevOps requires Jenkins to be reachable from Azure DevOps), as well as avoid the overhead of Git polling.