In situations where a player is smushed, such as by a scrap heli, or a vehicle landing on them, or hitting the ground too hard while in a vehicle (leading to their demise), their backpacks are being observed to have clipped through the ground and can be found below the world in the water there. This appears to be an edge case in the code, likely caused by the player body overpenetrating the ground.

Is there a fix for this?

Do you know whether the backpack spawned below the ground, or was the backpack pushed below the ground by the scrap heli?

There used to be an issue where a player's corpse would sometimes push their own backpack through the terrain, which we solved by disabling collision between corpses and backpacks. If your issue is caused by collision between the scrap heli and the backpack, we could possibly resolve it the same way, by disabling collision between backpacks and scrap helis (or vehicles in general), but we will have to take into consideration how to do that without creating other problems such as backpacks falling through scrap helis when a player inside dies. If the issue is that the backpack is simply spawning below the terrain, we can probably add some simple logic to raise the spawned height of the backpack if it's close to the terrain level.

WhiteThunder

Do you know whether the backpack spawned below the ground, or was the backpack pushed below the ground by the scrap heli?

There used to be an issue where a player's corpse would sometimes push their own backpack through the terrain, which we solved by disabling collision between corpses and backpacks. If your issue is caused by collision between the scrap heli and the backpack, we could possibly resolve it the same way, by disabling collision between backpacks and scrap helis (or vehicles in general), but we will have to take into consideration how to do that without creating other problems such as backpacks falling through scrap helis when a player inside dies. If the issue is that the backpack is simply spawning below the terrain, we can probably add some simple logic to raise the spawned height of the backpack if it's close to the terrain level.

I was present for one situation last night. Player was driving a snowmobile off a ramp, hit the ground flat, died from impact. Backpack was nowhere to be found. Admin radar showed that it was directly below the player floating in the water beneath the world. Other situations which I was not present for include being smashed by a scrap heli (multiple instances because said user keeps getting crushed by another player they know's heli).

So to answer your question, I don't really know. I'm fairly certain that I didn't see the bag appear at all. So perhaps it spawned below the world because it could not find a proper coordinate to spawn at?