In 1.21.1 and before, canceling an EntityResurrectEvent would result in the entity in question to die normally as if it wasn't holding a totem of undying. Since 1.21.3 (and possibly 1.21.2? I tested on 4398-Spigot-60c9969-561ceb9 (MC: 1.21.3)), the entity does reach 0 health, but none of the other effects of death happen. Players holding totems don't get death messages and don't drop their inventory or experience, and killing entities holding totems doesn't award kills (and therefore advancements and statistics don't update).

How to reproduce:

The attached plugin (SpigotBugReport20251217.jar) listens for all instances of EntityResurrectEvent and cancels them.

1. Start a server with the attached plugin.
2. Give yourself a totem of undying.
3. Die of any natural cause or to any mob.

Expected result:

Canceling an EntityResurrectEvent would cause an actual death.

Observed result:

Canceling an EntityResurrectEvent just sets the entity's health to 0 and doesn't otherwise cause a real death.