Recently, I found a possible bug or exploit where you can go above the world border (4096 Y) using Levitation effects. Any levitation effect works as long as it's on a repeating command block..

What I expected to happen was...:
Once I went above the world border, the levitation effect immediately cancelled or gradually cancelled out.

What actually happened was...:
The levitation effect never wore off.

Steps to Reproduce:
1: Setup a repeating commandblock affecting a player with Levitation and power it.For example:
/effect @p levitation
2: Teleport yourself to Y=4090 and wait the few seconds for the Levitation effect to lift you above world height border.
3: Notice that it lifts you above world border.