Ender dragon riding wither makes the duo zoom off very fast in one direction

When the ender dragon is riding the wither, it causes them to move in one direction very fast.

Steps to recreate:

1. Run /summon wither
2. Run /summon ender_dragon
3. Optionally run /ride @s mount @e[type=ender_dragon,limit=1]
4. Run /ride @e[type=ender_dragon,limit=1] mount @e[type=wither,limit=1]

Extra information:

When I run the command blocks like in the recording, the wither and ender dragon fly south. However, I did this without command blocks originally (manually running each command) and the ender dragon and wither went in a different direction. I suspect it has to do with which way the wither is facing when the dragon starts riding it.