If an ender dragon with NoAI: 1b intersects a velocity-affecting block like water or lava, this velocity will not be cleared. As a result, it will grow boundlessly. Note that velocity will be reset when the ender dragon has AI re-enabled, so there shouldn't be any issue with the ender dragon attempting to move across thousands of chunks from built-up velocity.
Steps to reproduce
1. Run the following command to spawn an ender dragon:
/summon ender_dragon ~ ~ ~ {NoAI: 1b, Silent: 1b}2. Place flowing water over the ender dragon
3. Run the following command to see the velocity of the ender dragon:
/data get entity @n[type=ender_dragon] Motion4. Repeat above command and observe how the values change
Linked issues
relates to 3
MC-302530
Immovable mannequins accumulate all movements they try to make and immediately perform all of them when made movable
Open
MC-303389
The ender dragon's velocity can be affected by attacks while perched
Open
MC-303390
Mobs with no AI accumulate all movements they try to make and immediately perform all of them when given AI
Open
Can confirm: