How do Image transformation billing work?

export const getFilePreview = async (fileId: string) => {
  const fileUrl = storage.getFilePreview(appwriteConfig.storageId, fileId);
  return fileUrl as string;
};

Developers are confused about how image transformation billing works. They are not sure if they are transforming images but are making around 50 transformations. They are using a function `getFilePreview` to get the file URL. They are unsure if they should store the entire URL or just the fileId in their database to reduce bandwidth consumption. Storing just the fileId might help to reduce bandwidth usage as the function `storage.getFilePreview` could be using bandwidth.