It is true that everything is gluten-free, but not because they make it in the kitchen. If not, they buy everything pre-cooked from Mercadona. The potato omelet is not homemade, nor are the croquettes or the meat in sauce. It is a scam and they take advantage of celiacs by saying that it is 100% gluten-free. It is much more profitable for you to go to Mercadona and buy it yourself, than to go there and eat four croquettes with lettuce and a mini piece of tortilla for €12.
The service was horrible and the food tasted like it was bought, heated and put on plates.
A place not recommended, there are more original places with good gluten-free service that are worth it.