A ghoul bite - a little extreme?

Recently passing dunge noticed an interesting effect imposed on me by ghoul - poisoning that has no timer and therefore lasted on the character until the end of the battle.
Looking closer at the information about the ghoul saw "Unclean - melee attacks have a 10% chance to poison enemy. That’s it.
At the same time, the poisoning of the usual type can be applied to the character at the same time with this effect (what happens in this case - does vulnerability grow?)
Today specifically “armed” treatment spell with a 30% chance of clearing the negative effects went to meet with ghouls)
I can’t guarantee that I set the truth because randomness plays a big role here, but of all my attempts to heal myself from this effect, not one worked. At the same time, the usual poisoning, burning, and other effects were perfectly cured.
So what was it? A little extreme in the game or a bug?
And I personally do not judge whether to keep this effect in this form or turn into a regular poisoning - after drinking levels of ghouls from Baldur Gates these incurable poisoning look like a runny nose! :slight_smile: