Description

If you fly into a wall using the Elytra then your head will be able to travel through blocks. I also think this can be caused when you are flying and get hit by a Shulker Bullet.

I recorded a short unlisted YouTube video to show this (it was too big to upload here): https://youtu.be/WinNci0BR2c

How to reproduce

Try flying into a wall using the Elytra, then go under a 2 block ceiling and jump, you will then go through the block.

How to stop

When this bug happens, I have found entering and leaving flight mode (with Elytra) makes it normal again.