If the theme of your store uses a non-white background, it can sometimes lead to poor user experience regarding the display of products on the Wishlist page. See for e.g. below. The background around product doesn’t match with the theme colors.
In order to fix this, all you need to do is to add a small CSS code to the Box 2 of Extra CSS tool.
.buttons,.product {
background: initial !important;
}In your Shopify Admin, the Extra CSS tool can be found at Apps => Smart Wishlist=> Configure Appearance => Extra CSS