[Bruman]

Isn't this a case of the client being wrong, but everything actually being fine? As in,your health was never actually 12, the client just thought so for a second. You were never in a risk of dying.

Also, is this related to, let's say you're fighting two mobs. One is as 100%, the other is at 50%. You're targeting the one at 50%. When you switch to the 100% one, the health will show at 50%, then animate up to 100%. When switching back to the 50% one, it'll animate down. It just immediately jump to the actual health. That's just how the client behaves.