Here is how you can prevent new products from being automatically pushed to Google's shopping feed.
As soon as you sign up and complete the setup, you can see that by default, your product status shows as "opted in." This implies that we attempt to push your products Google Merchant Center once you have successfully selected a subscription plan.
However, the "opted in" status is temporary. After Google has successfully analyzed the products, you will see the status has changed to "approved," "disapproved," or "approved with warnings".
If you do not want to send all the products to the Merchant Center, you can follow the steps below to change the settings.
Step 1: Click on Settings>Feed.
Step 2: You can go to Product Settings and unselect the default selection
You can always select the products manually and click on "opted in Google" or "opted out of Google" as per your requirement.
In case the default setting is "opted out," you should take special care while adding new products to Shopify; you have to select the new products and opt them in manually.