During the initial configuration of Katana x Shopify integration, you can choose whether or not you wish to import custom items on Shopify Sales orders to Katana.
If switched ON, Shopify custom items will be created as products in Katana. A new product will be created for each custom item and custom items are not matched to products existing in Katana.
If switched OFF, custom items will not be imported to Katana and will not appear on Sales orders synced from Shopify.