I don't think this has anything to do with fall damage. It's sort of like the elytra, where you zoom into the floor and die from kinetic damage. Also, your death message said <playername> fell out of the water, not "Hit the Ground too Hard" or "fell from a high place".
Because you were riptiding so fast, it hits the ocean so hard that the water doesn't stop you in time and you die form "kinetic energy".
I don't think this has anything to do with fall damage. It's sort of like the elytra, where you zoom into the floor and die from kinetic damage. Also, your death message said <playername> fell out of the water, not "Hit the Ground too Hard" or "fell from a high place".
Because you were riptiding so fast, it hits the ocean so hard that the water doesn't stop you in time and you die form "kinetic energy".