I respawned the ender dragon for the second time ( my third encounter with the dragon in that world) and after I killed the dragon the dragon egg did not spawn again. I was palying on 1.16.1 in bedrock in full survival and the egg dissapeared. Everything else was normal the anmation of dying happened, It gave me xp and the new thingy that you use to go to end cities did spawn  but the egg did not. (Sorry if I had some errors in my grammar or something)