Why does my iPhone 11 with iOS 17.1 say my hardware is iPhone 12,1?

As stated in the other thread you did the number is solely a model identifier for Apple and is not something to be concerned about. Model identifier 12,1 is indeed an iPhone 11. Like the iPhone 15 Pro Max is 16,2. iPhone 15 Pro is 16,1. iPhone 15 Plus is 15,5. For the 11 series the numbers are 12,5 for the 11 Pro Max. 12,3 for the Pro. 12,1 for the 11.

Because that's Apple's identifier for your model.

(246406)