How to add multiple required labels on "githubRunner"?

[Mkublbock]

We are using runners for two different purposes:

1. Build our Apps
2. Deploy to On-Premise Environments

Our build Runners all have a label "build" and the Deployment Runners all have "OnPremise". We are using both githubRunner and runs-on

  "githubRunner": "self-hosted,build",
  "runs-on": "ubuntu-latest",

Obviously for the githubRunner setting we don't want the builds to run on one of the on-premise deployment runners. It seems that using "self-hosted,build" together still sometimes uses an on-premise runner. But the setting also doesn't accept an array. How can we fix this?