$599 for 128GB with this caveat..
>Available space is less and varies due to many factors. A standard configuration uses approximately 12GB to 24GB of space, including iOS 18 with its latest features and Apple Intelligence on-device models can be deleted if Apple Intelligence is turned off and use approximately 7GB of space. Turning on Apple Intelligence will download the models again. Apple apps that can be deleted use about 4.5GB of space, and you can download them back from the App Store. Storage capacity subject to change based on software version, settings, and iPhone model.
That's just saying "The hard drive is 128GB, but your user directory only gets what the system doesn't need". Not at all surprising?