This rumor is based on internal documents obtained by MacRumors. Apple advises an authorized repairer to update the iPhone to the latest iOS before repairing, assuming that the camera button will not work properly unless it is iOS 13.2 or later.
originallyBattery case image found in iOS 13.2From this fact, it is speculated that this unpublished product is not supported in earlier versions because of the expected circumstances.
Apple also says that to avoid unintentional behavior, it reminds customers that the camera app won't launch after a quick button press. To open the app, you need to press and hold the button a bit, but do n’t forget to close it and return to the lock screen.
Apple doesn't recognize these events as issues of publishing official support documents, but rather a policy of eliminating customer confusion one by one.
iOS 13.2 is an update that has already been distributed, and the long press of the camera button on the lock screen is the same operation method used on conventional iPhones. Apple may not be confused by many customers, and it may seem that the initial confusion will naturally end without widespread attention.