On a realm, was in an End City, while fighting a Shulker at full health, I was instantly transported back to the realm spawn point in the over world. I had lost my stuff, but I did have my experience, so it did not seem like a death.

Leading up to this I had died in about the same location from fall damage, but it was when I returned to the same End City that I was teleported. When I went back the third time I retrieved my stuff and was not able to replicate the issue.