Ars Elemental: Ars_Elemental-1.19.2-0.5.8.2.jar

I found a Poseidon's Steed book that let me summon 2 dolphins.
When I right-click on it to ride it, it does not move.
When I press the Jump bar, I kind of teleport a few blocks.

Another detail worth noting is that it will go up and down according to where you're looking. So to jump in the right way you probably have to look up or it will have some issues

It doesn't move to avoid it wandering away. The fact that you can't steer it is weird, it works on my side.
Spacebar does indeed look like teleportation if used deep underwater, not sure why it doesn't dash smootly as it should, but it works when near the surface. I might have to add an hint in the docs, but the intended way to use the dolphin is to remain close to the surface and time the jumps to gain speed. Otherwise it's a bit slow, but allows to have infinite air while riding, to explore the depths early.