This is required to create new products while adding to the cart. Because the platform doesn’t allow dynamic price modification in the cart and every product comes with a new image (with customization).
These created products will not show in your storefront, storefront search or in google search.
Also, without a new product, it is not possible (in Shopify) to save the customization information (every customization is new) over a single product. These created products will be automatically removed after 1 month.
If you want, you can remove them manually, if you do not want to wait for the automatic removal.