The issue here is that Apple is facilitating wire fraud, which is extremely illegal in the United States. The bad actors who created that app are committing wire fraud on an Apple platform, which is of course colloquially known as the App Store.

The problem is that if you are associated with a crime committed in the United States in any way (besides being a very distant third-person witness with no associations whatsoever to the individual), and you are not a crime victim or an individual reporting the crime, you are almost always considered to be an _accessory to the crime_ which is a misdemeanor (go to jail for up to 365 days) or felony (go to prison for over 365 days) state level (has parole for prisoners) or federal level (effectively has no parole for prisoners) criminal offense, which the police will arrest you for and charge you with, while the person committing the misdemeanor/felony gets charged with whatever crime they perpetrated.

For example, if your "acquaintance" shoplifts at a store and gets caught, and you don't stop or report them: you will get charged as being an accessory to a crime and you're going to jail.

Also, if you are involved in an altercation in any way, the cop can put everyone involved in handcuffs and charge them, even if you never got physically or verbally violent.

There are also catch-all laws in the US that one can go to prison for, basically for acting in "bad faith" but never actually doing anything else criminally wrong.

This is why you never talk to the police, ever. They will twist your statements in the wildest ways imaginable. If you get pulled over by the police, you should practice, every single time, saying as little as possible to the officer.

This has never happened to me personally, but, everyone needs to know this: If the police in America start questioning you and it gets into a detailed discussion, you stop right there and say: "No comment: I need to talk to my lawyer first."