The Unexpected Link warning is issued in the following situations:
'Validation' should be set to '(none)' in links with 'Method' set to 'Navigate': you have a Link widget with the Method property set to Navigate and the Validation property set to either Client & Server or Server. To validate the end-user typed values, you have to submit them. See Validate End-User Inputs.
Edit your Link and set the Validation property to (none) or change the Method property to Submit. Learn more about different behaviors of the Link widget.
'<destination_screen>' should be either a Frequent Destination or the target of a connector from '<originator_screen>'.: you are using destination_screen in the property Destination of a Link or a Button widget in screen originator_screen. Neither a connector exists from originator_screen to destination_screen nor does destination_screen have the property Is Freq.Destination set to Yes.
Edit your web flow and connect the two screens or set screen destination_screen property Is Freq.Destination to Yes.
If you were explicitly trying to disconnect the two screens, you must edit the property Destination in the originator_screen widget and select from the drop down list either (none) or a different destination.
Clicking the symbol will launch the Link widget properties where the warning was detected.
About Link | About Warning Messages