You might have received an email from Google Merchant Center recently stating that you have missing items that will be automatically added as of June 22, 2024.
In most cases, especially if you have your integrations done with us, you don’t want this feature to be enabled. Fortunately, even though it will be enabled by default, it won’t include those items in your Shopping campaigns. However, we recommend disabling it when you have the chance.
The reason this feature is not necessary is that those items are either excluded from the feed due to optimization needs, or being out of stock, or because the item ID you use for those items in the feed might differ from the item ID your microdata shows in the source code of your product pages.
For example, in the case of Shopify, where this issue is most common, people often use the prefix shopify_{COUNTRY}_{parentid}_{variantid} due to legacy settings when enabling things using Google’s Shopify app, but their microdata often uses SKUs.
Google's bots determine whether an item is included based on the IDs they see in your source code. If different IDs are used as described above, Google is not actually adding new items but duplicating those already there with different IDs. Often, they also add these items without any extra attributes such as gender, age group, GTIN, etc., because these are often not available to their bots.
In conclusion, that email is often incorrectly stating that you are missing something when, in fact, you are not. This is why we recommend keeping that feature disabled when possible to prevent duplications or items with incomplete attributes from being included.
If you have any questions, feel free to get in touch using our contact page.