Question about Get Velocity

When I use the Get Velocity node, I would expect that breaking the vector would give me the rate of speed in each direction as a float. However, when I print the Z output from the node, I usually get a slowly decreasing number even when I’m moving on an even surface. Why is this, and what can I do to get the current Z speed of the character?

Edit: I should note that this occurs when I’m making a character lock it’s movement along a spine. So That probably has a lot to do with it.