Traveler's backpacks that are equipped with the mods own equipping up arrow method are not saved to the body player or grave upon death, which means that every single thing in the bag is gone upon death.

Pardon me, I was incorrect. The bag is not saved with the grave, but, it does float at wherever you died, which means that if you died over the void like I just did, the bag is not with your grave, rather, it is at the very bottom of the void, floating, waiting for you to recover it.