No idea where I should report it so imma just put it on all three githubs I guess.

Using
Inventorio https://github.com/Lizard-Of-Oz/Inventorio
Gravestones https://github.com/Geometrically/Gravestones/issues
Requiem https://github.com/Ladysnake/Requiem

If you die while possessing a mob, weird stuff happens.

• a grave gets created, but most of the items just fall out like normal rather than go into the grave
• your currently selected hotbar slot, offhand slot gets deleted
• your currently selected toolbar slot (i was mining while it happened) gets duped

My inventory before I died

My inventory after I died BUT before I broke the grave (all these items were on the ground)

My inventory after picking up what was in the grave too

Inventorio's author here:
So far it seems to be a mod conflict between Gravestones and Requiem - even without Inventorio they have issues. But each of them separately seems to work fine with my mod (aside of this, which I'm currently fixing)
Also, having Gravestones and Requiem together causes issues with /gamerule keepInventory true.