The Exclude thumbnail sizes option is very useful when it comes to reducing your credits consumption. However, the first question that arises: how do I know which thumbnails to exclude?
The real answer is that it depends on where you used each thumbnail size on your pages. Only the person who built the website will know if a particular thumbnail size is used on your website, but perhaps your theme provider can help as well since most thumbnail sizes are created by themes. They will know where each thumbnail is supposed to be used and for what purpose.
However, there are some thumbnail sizes that are used on many websites, and here’s what they do:
thumbnail: Corresponds to the Thumbnail size in Settings > Media.medium: Corresponds to the Medium size in Settings > Media.medium_large: Created by WordPress.large: Corresponds to the Large size in Settings > Media.1536x1536: Created by WordPress.2048x2048: Created by WordPress.woocommerce_thumbnail: Created by WooCommerce, used in the product ‘grids’ in places such as the shop page.woocommerce_single: Created by WooCommerce, used on single product pages.woocommerce_gallery_thumbnail: Created by WooCommerce, used below the main image on the single product page to switch the gallery.shop_catalog: Created by WooCommerce, it’s an alias forwoocommerce_thumbnail. It doesn’t generate an additional thumbnail.shop_single: Created by WooCommerce, it’s an alias forwoocommerce_single. It doesn’t generate an additional thumbnail.shop_thumbnail: Created by WooCommerce, it’s an alias forwoocommerce_gallery_thumbnail. It doesn’t generate an additional thumbnail.