A good introductory explanation: https://coldbloodedscience.com/the-art-of-shape/
I imagine that a failure of connection between brain and hands is possible though. We wouldn’t call it “stutter” normally (it would probably surface as some kind of tremors), but effectively it would be a sign language alternative to stuttering.
But why does it appear in my post but not in posts of others’? Is it link-specific, or something?