Product Auto Update
If this feature is enabled, any changes that you make in the products feed on Shopify, then it will be automatically reflected for that particular product on Facebook Marketplace, Facebook Shop, and Instagram Shopping.
(If enabled) If any new product is added to the Shopify store, then that product would be automatically added on Facebook Marketplace, Facebook Shops, and Instagram Shopping.
With this setting, the product would be automatically deleted from Facebook once it is deleted from Shopify.
Which field to update
Assign a field for your product like title, description, price, image, brand, inventory count, and category to your products.