Riding a Pig, while holding a carrot on a stick, will set all of the pigs Motion Values to 0. This ignores potion effects such as Levitation and Slow falling and will cause the pig to just fall at the normal speed and Die.

Put More Simply, If you are riding a Pig with a Carrot on a stick, it will always fall at the normal speed, regardless of potion effects. It also makes makes the motion value for the pig unusable for commands when the player riding it is holding a carrot on a stick. 

This also will ignore tp commands and attempting to teleport the pig will do nothing.

Switching off of the carrot on a stick will allow the pig to experience these effects again.

With no potion effects, you can switch on and off of the carrot on a stick to keep resetting the pigs vertical motion in game. Pig still takes damage when hitting ground though.

In attached screenshots, the data im getting is @s RootVehicle.Entity.Motion