The Bug:
Boats and rafts sometimes rapidly jitter when colliding with entities.
Please note that this problem cannot be reproduced consistently; it make take a while for you to experience it.
Steps to Reproduce:
Locate an open body of water and summon several pigs riding boats by using the command provided below multiple times.
/summon minecraft:oak_boat ~ ~ ~ {Passengers:[{id:"minecraft:pig",Silent:1b}]}
Obtain a boat, place it down, and begin riding it.
Collide with other nearby entities multiple times and from varying angles.
Take note as to whether or not boats and rafts sometimes rapidly jitter when colliding with entities.
Observed Behavior:
Boats and rafts sometimes rapidly jitter.
Expected Behavior:
Boats and rafts would never jitter.
Related issues
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Comments

I can confirm this behavior.

Can confirm in 1.19.4

I cannot reproduce this bug in 1.21.3, unless I am reproducing it incorrectly.
Also, the command provided no longer works in the latest version. Use the following command instead:
/summon minecraft:oak_boat ~ ~ ~ {Passengers:[{id:"minecraft:pig",Silent:1b}]}
I also was unable to reproduce the issue in 1.21.3, the collision seems to be far more improved.