I was in the nether and I somehow walked into a 1 block tall space and suffocated for a bit.

It seemed like (in the nether) the player's hitbox only covers the player's legs.

I have a video file that might help things, but it was too big, so I have a google drive link:

https://drive.google.com/file/d/1duUNvfGunUHoVTPubRIHFr72Inn2IA1o/view?usp=sharing

Update: I've found that it happens in the overworld and the nether (not sure about the end).

But I have found a way to activate it purposefully.

1) Be on a world in survival for more then 30 mins (I do alot of projects on my survival world).

2) Find a flat wall more then 2 blocks and stand infront of it.

3) Place a block infront of you (it might not work, if it doesn't just stay on the world for longer).

4) And continuously right click, and you may have an x-ray glitch. But if you can place a block on your head, then you should be able to walk through 1 block gaps.

 (it also helps if you have an elytra)

I'm not sure about multiplayer and I'm not sure if lag helps, but I'll update this issue if anything else happens.