Hi Rich,
Thanks for posting your concern.
The average position metrics, after it has been sunset, will only return null values (represented as two dashes "--" in the reports) as stated
here. That said, historical data would also no longer be available. If possible, you may already apply changes on your end to no longer include the said field in any of your requests as it would no longer provide any usable data after the sunset date.
Also, I would like to recommend that you keep an eye on our
blog for any other changes, updates, or announcements regarding this topic. I hope this help
Regards,
Ejay
Google Ads API Team

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