This doesn’t happen with any other skin. Her animations essentially freeze for a few seconds after you perform an action. The best way to see it is to auto attack something and move immediately after; she will slide around stuck in the attack animation. Also happens with basic abilities and the mount/hearth channeling animations.
This has been happening to me too. Just as with you, it’s only when using her Witch skin. Hope they can fix this soon! It’s one of my favorite skins and it currently feels bad using it.
Known Issue/Tracked - Thanks!