As noted by MacRumors, Apple plans to implement a change to the iPhone’s internal clipboard that will prevent Mac apps from being able to read pasted info without a user being alerted.
Here are some delays from Apple’s developer page: Prepare your app for an upcoming feature in macOS that alerts a person using a device when your app programmatically reads the general pasteboard. The system shows the alert only if the pasteboard access wasn’t a result of someone’s input on a UI element that the system considers paste-related. This behavior is similar to how UIPasteboard behaves in iOS. New detect methods in NSPasteboard and NSPasteboardItem make it possible for an app to examine the kinds of data on the pasteboard without actually reading them and showing the alert. NSPasteboard also adds an accessBehavior property to determine if programmatic pasteboard access is always allowed, never allowed, or if it prompts an alert requesting permission. You can adopt these APIs ahead of the change, and set a user default to test the new behavior on your Mac.