Thanks for your answers, rahsut and Jgodfrey!
My bad, it's not a "button" in that sense, I should have elaborated that earlier. It's a self-made "button" (Area2D - CollisionShape2D) including several functions like "ontimertimeout" and "onArea2Dmouse_exited" and alike. There are things happening within each of them like animations including yields, and during those I'd like to have any input disabled. So I guess "button.disabled" won't work in this case.
I've been looking into "inputpickable" before, because I think that might be what I need here. Probably a typical beginner-issue, I just couldn't find out how to build it into my script! (I, the brginner, sometimes stumble over things, like in the documents, that look exactly like what I need, but I have no idea yet how to implement them. If only there were little examples shown in those places... I'm certain most beginners know that feeling.)
Could you tell me how I can actually "use" inputpickable?
Thanks for your help!
THE BIG EDIT:
I just learned:
get_node("your_area2D").input_pickable = false does the trick!