Cloud Build Trigger returns 14 UNAVAILABLE: 502:Bad Gateway

Using the JavaScript library, NodeJS-CloudBuild we've been able to write a Cloud Function that triggers a new Cloud Build whenever we need.

It's been stable for a few months, but starting monday, we've been getting an inconsistent error whenever we call the function: Error: 14 UNAVAILABLE: 502:Bad Gateway

The code sample is pretty simple, taken straight from the repository but with our variables.

  // Creates a client
  const cb = new CloudBuildClient();

  // Starts a build against the branch provided.
  const [resp] = await cb.runBuildTrigger({
    projectId,
    triggerId,
    source: {
      projectId,
      dir: './',
      branchName,
    },
  });
  console.info(`triggered build for ${triggerId}`);

I'm not sure what changed recently to cause these return errors. It works fine when doing a "manual" trigger from the Cloud build dashboard, too.