Technically, the vault key is stored in several copies, each copy is encrypted by the personal key of a user in the group, or a recovery user to reset the vault

Technically, the vault key is stored in several copies, each copy is encrypted by the personal key of a user in the group, or a recovery user to reset the vault key. > Then what is the entire purpose of such services, if their providers still need to be blindly trusted? Even if the provider doesn't have direct access to the vault key, you have to trust the provider at the moment you access your vault, because the server is controlled by the provider.