Why did Google leave Appen?

Could you please explain the reasoning behind Google's decision to part ways with Appen? Was it due to performance issues, changes in strategic direction, or perhaps a disagreement over terms and conditions? It seems like a significant move that has left many in the industry curious about the underlying factors. Did this decision come as a surprise to Appen, or was it a mutually agreed-upon parting of ways? I'm interested in hearing your insights into this matter.