When a player that is riding a horse, throws an enderpearl, he is only dismounted and does not get teleported.
Steps to reproduce:
Start riding a horse. While riding, throw an enderpearl.
Expected result :
The enderpearl would teleport the player to wherever it land
Actual result :
The player simply gets dismounted.
I don't remember this being the case in older versions.
I am able to reproduce the reported behavior. It was introduced in 1.21.4 Pre-Release 3.