Teleporting a mob while riding it will cause a visual glitch and deviate the rider. The following example uses a chicken as the vehicle.
Steps to reproduce
Run this command to summon a chicken:
/summon chicken ~ ~ ~ {NoAI:1b, Saddle:1b, CustomName:"\"chicken\""}
Set up a repeat command block with this command:
/execute as @e[name=chicken] at @s run tp @s ^ ^ ^0.35
Run this command to ride the chicken:
/ride @s mount @e[name=chicken]
Expected Results
The player rides the chicken without any offset while it goes forward, like in Minecraft 1.19.4. (video: "1.19.4_ride_expected").
Observed Results
The player rides the chicken with a offset and it shakes while it goes forward. (video: "23w18a_ride_bug").
This might be the same issue as MC-261202.