The reference icon is set with the following properties:
Release or Environment
The property glide.ui.clickthrough.popup has been set to true.
The behavior that you are seeing in the popup browser window is expected behavior and cannot be modified to display the related lists, please see the following documentation:
it states: "glide.ui.clickthrough.popup:
Enables (true) or disables (false) displaying the pop-up diamond icon for a reference field and opening a new window when the icon is clicked.
Note: Related lists do not appear on forms opened in the pop-up window."