The method toAfricasTalking() does not exist on Illuminate\Notifications\Notification. It seems like you code against a sub-type of Illuminate\Notifications\Notification such as NotificationChannels\Afr...g\Test\TestNotification.
(
Ignorable by Annotation
)
If this is a false-positive, you can also ignore this issue in your code via the ignore-call annotation
This check looks for calls to methods that do not seem to exist on a given type.
It looks for the method on the type itself as well as in inherited classes or
implemented interfaces.
This is most likely a typographical error or the method has been renamed.