Dark Night needs more sustain ofc.
But, as a healer main. I don't think us, healers (except some silly player there can be out there) are thinking in griefing any tank lmao. We just want to do the duties.

But if a healer sees you at 200 hp, as they don't want you to die, will try to raise your health fast to make sure you don't die.

Not all buffs are shown in the party, only some of them and also not everyone is like "oh, tank at 200hp, let's have a look at his buffs, does he have living dead active?"

So, ok, dark knight needs more sustain and living dead should have a way of fixing this issue.

But wtf no one is griefing you.