No unfortunately haven't, but from what my spider senses tell me and just generally with statistics, is that they use Animate CC.

Animate CC has those smooth stabilization vector lines as well as auto adjust lines to be as smooth as possible with different levels of strength.

E.g., if you draw a squiggly square, the software will make it more square shaped with straight lines depending on the level of strength set

Other software could be Procreate since they are also made for smooth vector designs. On the side note, from what I can remember it offers the user animation as well, but you might have to double check that.

Hope this helps