When you fly in Creative or Survival mode with elytra to 600-700 blocks in the sky, when you come back down, there will be massive unloaded chunks for about 1-3 minutes. Then there will be small patches of unloaded chunks for about 15 seconds more. Then everything is back to normal.

Steps to reproduce

1. Get an elytra
2. Go to y=600-700
3. Come back down

Observed results

Massive unloaded chunks

Expected results

Very little unloaded chunks