Whenever someone dies in the end there's a seemingly 50% chance the realm will crash. Upon going back into the realm, the save has been reverted to the most recent backup. It doesn't seem to matter how the player dies, as various people have died from falling and hitting the ground too hard, falling out of the world and being killed by endermen, all of which have (sometimes) triggered the realm to crash.

We've seen this issue on versions 1.17.11 and 1.17.30 (we didn't really go to the end before these versions)

The map being played was created over a year ago and uses no experimental features.