Steps to reproduce the issue :
1.Find an buggy elevator kind of thing
2.Keep jumping on it until the thing left you in mid-air
3.PROFIT
4.???
5.Fly
Screenshots / Video :
Steps to reproduce the issue :
1.Find an buggy elevator kind of thing
2.Keep jumping on it until the thing left you in mid-air
3.PROFIT
4.???
5.Fly
Screenshots / Video :
Confirmed. The world is flat. 
And now you’re in space.
This happened to me! I used a warp scroll to get out. I don’t know if changing channels or relogging woud’ve fixed it. Also got stuck under a rubble stairs at Pelke Shrine and teleported to get out.
cheaper fix would be to use your warpstone.
remember, that weird grey “personal coat of arms” looking thing that you started with. check in your Quest Items section of the inventory.
For who got stuck by this, there are some solutions: