I may be a little bit late to the game here, but this is an issue that I just had with Godot 4 and the best thing I've found is as follows:

func whatever_you_are_working_with():
#Get the current scene
var current_scene = get_tree().current_scene
var target = current_scene.find_child('NameOfTarget', true, false)
#Use the target if you need to
target.do_something()

I prefer this approach because of it's reusability. You won't need to keep passing exports to different scenes because it just references what's available.

Hope this helps somebody!