Keep inventory seems to have turned itself on and I can't turn it off

My girlfriend and I have been playing a LAN world just the 2 of us, its my world and she joins via lan, we are both in survival mode and I have cheats disabled,

I also have several datapacks for vanilla tweaks including the graves pack (does as name suggests instead of your items exploding from your body a grave spawns that only the player who it belongs to can access) this has been working fine for the last month or so but recently both she and I died in the Nether and instead of graves being spawned our stuff stayed in our inventory (we both died in lava so maybe something to do with that)

EDITTED: i just tested it in the overworld and both dying in lava and falling my inventory stayed