Hi and welcome to Arturia forums.
I don't have the controller.
But it look like you for both pads and keys can set minimum and maximum values for aftertouch.
Have you set both the minimum and the maximum values to 0? If and only if you set both to 0, then i would think there skould be no effect.
A button on a controller to easyli switch things like aftertouch and velocity on and off could in some cases be a nice and useful feature.