PR triggers on any commit

Hey all,

I'm working on an Azure DevOps pipeline that I would like to fire ONLY when a pull request is issued targeting the main branch. The repo is sitting on GitHub. My yaml looks like this:

pr:
  branches:
    include:
    - main

I created a new branch called pr-test-1 from main. Made a few changes to my local copy and pushed the new branch to the GitHub repo. This triggered the pipeline even though I had not created a PR for pr-test-1.

I tried changing the include to an exclude, but that did not fix it. Am I completely misunderstanding how the pr trigger is meant to work? Or is there something I need to change on my GitHub repo?

Thanks for any help!