Update
I asked Tristan Jones about this exodus one-shot.
It turns out that's not Newt drowning in her cryotube (it totally looked like that to me too). It was a flashback sequence from an original story he was working on years ago in which a young girl wakes up in the middle of cryo sleep and witnesses her mother being torn in half after their ship is hit by debris from a nearby asteroid that exploded due to a mining accident.
Visually, it's heavily inspired by alien so it really does look like Newt in cryo right before she drowned.