I am having a problem where if an attack deals enough damage while i am on 1 heart, my health will be fully healed

the mobs in question which are dealing the damage were sharks and big cats from the untamed wilds mod. I also had the problem one time with a drowned wielding an axe.

I apologize for such a late reply. I've been unable to replicate this so far. Do you know of a consistent way to replicate it?