When the ender dragon is riding the wither, it causes them to move in one direction very fast.
Steps to recreate:
Run /summon wither
Run /summon ender_dragon
Optionally run /ride @s mount @e[type=ender_dragon,limit=1]
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.
Thank you for your report!
We're tracking this issue in MC-69881, so this ticket is being resolved and linked as a duplicate.
If you would like to add a vote and any extra information to the main ticket it would be appreciated.
If you haven't already, you might like to make use of the search feature to see if the issue has already been mentioned.
Quick Links:
📓 Bug Tracker Guidelines – 💬 Community Support – 📧 Mojang Support
📓 Project Summary – ✍️ Feedback and Suggestions – 📖 Game Wiki