When using four end crystals to resummon the ender dragon, the crystals explode at the end of the dragon’s respawn animation. If the player is in close proximity to these crystals, they can blow up. If they do, their items will be destroyed. Looking at the logs, there is a 0.002 second delay between receiving “The End… Again…” and being blown up. Visually, it appears that all four crystals explode simultaneously. However, they must explode with some delay or chain reaction in irder to also destroy dropped items.