Just for that case a new category of business classification was invented: the gatekeepers, and coincidentally almost all of those gatekeepers are American companies. Unlike antitrust regulation and other EU regulation that wan't based on clearly observed harm to the consumers, as otherwise that would have been covered by existing laws. It was solely designed to prevent businesses to have a potential ability to do something anti-consumer.
It is in fact an antitrust law. It basically argues (correctly in my opinion) that Apple and other companies have created new markets inside of their products. And in those markets they exert total control, including charging developers extortionate fees, forcing them to use their subpar and expensive payment systems or restricting what users can run on the devices they own & a lot of paid money for.