Last summer, Google started enforcing its new unique product identifier feed specification for Google Shopping. Google said it was improving support for merchant-defined multipacks. The feed specification clarified how multipack products should be submitted. As it moved toward high-resolution displays, Google also started recommending higher-quality images with at least 800 pixels in height and width.
For products like custom goods, vintage items, collectibles, etc., which don’t have unique product identifiers, Google introduced the “identifier exists’ attribute, and updated its requirements on unique product indentifiers.
Last year, Google began disapproving products that didn’t have data in the feed for the unique product identifier attributes, demoting products that incorrectly used the identifier_exists attribute, and disapproving products that provided invalid GTINs that didn’t conform to standard GTIN specifications.
You might want to check out this data feed discussion from the company:
Image via Google