I thought this was always implied. They’re always going to set it up for optimal settings, and that’s going to include all of the professional lighting and a (probably commercial) director.
They’re never going to show off what it looks like recording in terrible conditions because that won’t sell. They’re not technically lying either, because it is shot on the iPhone, just replacing the traditional cinema camera with an iPhone, which is actually a legitimate use case.
I use my iPhone for filming motorsports and it works out great. It’s not cinema camera worthy, but it looks pretty good.