Stain of Sin counter resets when drinking potion

Pretty much the title. I noticed while running a 2man grift that the counter was suddenly lower than before without spawning a pool. After suspecting that drinking a potion might cause a reset I tested this in a new game (by myself) and could reliably reproduce the behavior.
I also noticed a number of other things resetting the counter:

  • changing skills
  • changing equipment
  • zone transition

I also noticed this, even after the first patch (11.12). When I pick up an item from the ground, counter resets to zero.