Lost Trinkets: LostTrinkets-1.16.4-0.1.10
Forge: 35.1.36

When applying the Karma trinket, the cost of trades comes down from the base cost. For instance, I had paper trades that were originally 24 for an emerald. The trinket brought this down to 19. However, once I started zombifying and healing the villager I noticed the cost was not coming down.

I finally disabled the trinket and checked the price. It was already at 1 paper for 1 emerald. I then re-enabled the trinket and the cost shot back up to 19. So it appears to ignore other discounts.