Yea, so im a bit late to the party, but I figured out whats causing the infinite pumpkin mode bug. At least for me, if you die while in pumpkin mode, you never lose it when you respawn unless you pick it up again. Im not sure if it stops going away after you get down, or if it stops when you die, but I know for sure that when you die with the pumpkin mode you will keep it forever.