Hi Reggie,
Thanks for reaching out. The field metrics.average_position has already been sunset in the Adwords API and Google Ads API which was mentioned in this blog post. In lieu of average position, we recommend you use the new metrics of Impression (Absolute Top) %" and "Impression (Top) %. Please let us know if you have any further questions.
Thanks and regards,
Xiaoming, Google Ads API Team