When the dragon is killed, only 1 single end gateway spawns, instead of several gateways like in previous versions. 

Tested in 3 different worlds created in 1.16 Pre 5. I used creative to replicate the issue. To replicate:

1. Create new world in 1.16 Pre 5 (Creative is faster to test)
2. Go to the end through the end portal in the overworld. 
3. Destroy all end crystals and kill the dragon
4. Only 1 single end gateway portal spawns

Screenshots from all 3 tests are attached