We recently added gift cards to our store using the built-in Shopify functionality. When viewing the cart after adding a gift card to it, we are seeing buggy behavior with the quantity selector. If you click the + to increase the quantity, the quantity just changes to 0 and then the gift card is removed from the cart. And we are unable to manually type a quantity either, which also results in the gift card being removed from the cart altogether. Here is the gift card page for reference: https://nourishe.co/products/gift-cards. Please note that the quantity selector works fine for other products, so it seems to be an issue with the gift cards specifically.
We actually noticed two bugs that seem unrelated after adding gift cards. I already submitted one of them in a different post which I will link to in case they are somehow related: https://community.shopify.com/c/shopify-discussions/variant-selector-not-working-for-gift-card-denominations/td-p/1789892