That might be one of the perks with a 3d printed prop, the prop might break before the gearbox. We are looking into building an inserts in the prop that will break before the gearbox so the gearbox survives if there is something (jellyfish, wood or trash) entering the prop). It’s a mechanical safety in a way.
It’s a feature we have seen in our Mercury 40hp outboard motor, it’s like a small plastic cup that disconnects the prop shaft if the prop hits a rock. It saves the gearbox, and you can still drive slowly.