Use neither portal in the end,can cause a few problems.

When you use neither_portal(by setblock) in the end and you enter in it,you will teleport to the overworld.During this time,destruction block particle-free effect,and you can’t enter in any portal.Untill you exit the game,you can’t play normally.If you exit the game when you in end_portal,enter the game again,you will teleport the end that where you set the neither_portal.And that place will create a Obsidian Platform.