Suzie Voss

If this happens and you are stuck, you can escape the void by typing a /setblock command: /setblock ~ ~2 ~ minecraft:end_gateway 0 replace {ExactTeleport:1,ExitPortal:{X:0,Y:0,Z:0}}
Change the coordinates to a safe location and you should escape, as this will produce another End Gateway block immediately above you. (Try jumping if you don't immediately teleport to your set coordinates)
Please note you will need cheats enabled to be able to do this, and the horse has not been known to make it out the other side.

That is, if anyone (like me) is still experiencing the bug.

I have just come across a ticket with the same query, MC-91628, this can be closed as a duplicate.

If this happens and you are stuck, you can escape the void by typing a /setblock command: /setblock ~ ~2 ~ minecraft:end_gateway 0 replace {ExactTeleport:1,ExitPortal:{X:0,Y:0,Z:0}}

Change the coordinates to a safe location and you should escape, as this will produce another End Gateway block immediately above you. (Try jumping if you don't immediately teleport to your set coordinates)

Please note you will need cheats enabled to be able to do this, and the horse has not been known to make it out the other side 😞