Three instances in a Realm where someone died in the Nether and dropped inventory either partially or fully disappeared before the 5 minute timer. 

One instance involved being thrown by a Hoglin and dying of fall damage near a lava stream- when I got back, my netherite pickaxe was there, but none of my other things were, not even my netherite armor, assuming everything had landed in the lava. Some other miscellaneous items from my inventory were found about 20 blocks away, but I could not find the rest of my items. 

Second instance involved someone suffocating in a wall: items were not present upon return. 

Third instance involved being blown up by a bed: items were not present upon return.