The bug

Axolotls sometimes continue to move whilst playing dead.

To reproduce

1. Summon an axolotl.
2. Summon a drowned.
3. Wait for the drowned to attack the axolotl.
4. Eventually the axolotl will play dead.

Alternative reproduction steps:
(Note: this is just for easier reproduction purposes. Editing the NBT data of an entity during its lifetime is generally not supported and is not considered a bug. However, as this issue does occur without the use of commands, it is much easier to visualize it using these steps.)

1. Summon several axolotls.
2. Execute the following command:

   /execute as @e[type=minecraft:axolotl] run data merge entity @s {Brain:{memories:{"minecraft:play_dead_ticks":{value:1000}}}}
   

Observed result

Sometimes the axolotl continues to move whilst still playing dead.

Expected result

Axolotls would always stay still whilst playing dead.