My favorite definition of the (public) cloud is “It’s someone else’s computer.” That is really what any external cloud service is. And if your services, data and other assets are located on someone else’s equipment, you are at their mercy on whether you can access those assets and data at any time. It isn’t up to you. It’s solely determined by them, and any service level agreement you agreed to. And you can lose everything stored there permanently. You should have multiple backups of your data no matter where it is stored, especially including if it is stored using a cloud service.