Let's say the channel you are advertising on, such as Google Shopping, was previously listing your products from the Shopify API app. Your product ids will look like shopify_US_1324569878745_654789321456 or shopify_ZZ_1324569878745_654789321456. 

A custom rule is needed in your Google Shopping feed to use the same identifier, so your products avoid another 'review' by Google. 
 

Add a pre-built Shopify ID rule in FeedPilot 

In the 'Rules' page in your Google Shopping feed >click the "FeedPilot" button> filter for the [F].[id] field > then select the rule that matches the current format of your Shopify product IDs > click "Apply & review" or "Apply & compile" to add the rule.  

How to create the rule manually

Note, you must choose the [F] and [P] field names from the drop down lists, not copy and paste them.

SET [F].[id]

TO shopify_US_ + [P].[product_id]+ _ + [P].[id]

WHEN All products