If an API key is set from a constant in the wp-config.php don’t show the input field for that, but display a notification, telling the user that the API key is set through a constant.
Bug fix:
Fixed a bug that caused the map settings tab to show an empty panel when no API key is set. It now shows a notification.
Other
Rename the API Settings tab to Api Key.
The API key tab now shows a new field to use. Google changed the way keys are used. New users will only see this field. Users that have existing keys can still use them the old way, but are encouraged to use the new field.