Our workflow when creating new projects is to
create a master branch in github with 1 file in it.
on a branch create an initial project including a Jenkinsfile when that build passes merge it to master

but as of an update done in the last 2-3 days the pull request build isn't being created

Proposing repo
Looking up org/repo

  Getting remote pull requests...

    Checking pull request #1
    (not from a trusted source)
    Job name: PR-1
      ‘Jenkinsfile’ found
    Met criteria

  0 pull requests were processed (query completed)

The user is a 'trusted' collaborator, I verified using the api the code uses.

I think the change is related to:
https://github.com/jenkinsci/github-branch-source-plugin/pull/128

I have downgraded the plugin for now