Consistent part-
If a pokemon uses z-belly drum, and dies to recoil damage, the trainer of the pokemon that uses z belly drum glitches and /endbattle is needed. (recoil being double edge recoil damage, or rocky helmet/rough skin/iron barbs damage from a contact move)
Inconsistently-
When a pokemon with rough skin/iron barbs/rocky helmet faints as the same turn as the user, the battle is frozen, and /endbattle is needed.
Also works if user faints on the same turn as killing with recoil
After effects:
After /endbattle is used, the user's hp increases back up to what it was before rocky helmet happened.
Does not happen with-
Statuses (Burn, Poison, Badly Poisoned)
Weather Damage (Sandstorm/Hail)
Possibility of why its happening-
Innards out damage calculation may be funky with it, however innards out seems to work fine on its own.

Seems to be just belly drum in general. seems like when it didn't it was a fluke.^

Also includes Curse from a ghost type. after testing, Mind Blown may also cause this to occur, however as I don't have one of those atm, I can't test it. The reason maybe mind blown as well is because it also halves total hp and that seems to be the root bug.

This ticket is a duplicate of: https://www.pixelmonmod.com/tracker.php?p=2&t=14846