It looks like "clever" people at Apple removed the "priceTier" filtering option. You can see that the option is missing in their own manual https://developer.apple.com/documentation/appstoreconnectapi/managing-in-app-purchases#Manage-pricing-for-your-in-app-purchase as well as in the API documentation https://developer.apple.com/documentation/appstoreconnectapi/get-v2-inapppurchases-_id_-pricepoints Thank you, Apple, for making our lives harder & harder.

The removal is mentioned in App Store Connect API 3.5 release notes https://developer.apple.com/documentation/appstoreconnectapi/app-store-connect-api-3-5-release-notes