If you are getting this error after March 1, 2025, this is likely because the Places API is in Legacy. It's been replaced by the Places API (New).

If you still want to use the old Places API, or if you are using the Places API (New) and are still getting the same error, you can manually activate the old Places API by going to this link. You also might need to edit the API Key API Restrictions and add the Places API to it.