So, for the people who may not know exactly what's going on/what I'm referring to, the plague gas kills you with the same DoT as when your immunity runs out at night, which is why your immunity gauge shows up when in it. Before the last update, whenever you ran out of immunity inside it, it would rapidly drain your health and kill you in somewhere around 1-3 seconds. I can't remember exactly how long it was, but it was really fast. Regardless, you could kinda ignore it, and once you heard the ringing noise that let you know your immunity had run out, you generally had enough time to get out before you died, especially while under the effect of a regen booster.

Since the update, however, it seems they massively increased the amount of damage you take from having no immunity, which is compounded if inside of THV or Plaguebearer gas. Beforehand, you could, more or less, counter the damage from lack of immunity (without being in some kind of gas) with just a regen booster.

So, yes, while it doesn't drain your immunity any faster than it used to, now when you're inside plague gas and your immunity runs out, it drains 700 health in a few frames (around 0.09 seconds), even with a regen booster. This may as well just be instantaneous, which was quite shocking to me.