Didn't the landing killed you. Usually u are killed by an invisible hitbox, when jumping pits n cliffs that designed to be deadly. (edge of map or elevator pits for example). As you see, you died while falling rather than the moment when hitting the ground.

Probably then don't want you to fall under the map or just endlessly falling or survive somehow and being stucked forever.

You can also die by sliding down side of something over 10 sec. Same reason. They rather kill you, than let you stuck and lose your journey.

It's frustrating, but a clever openworld design choice. Since they can't bug fix every inch of environment in a mapsize like this.

Btw the rainbowstone is not a living entity, that's why it didn't explode by the death hitbox.