All cured villagers from past versions of the game (in my case, 1.16, 1.17, 1.18 and 22w15a), do not retain any of their discounts for trading when upgrading the world to the 22w17a snapshot.

Recreating this should be fairly straightforward, simply open up a world with cured villagers from a past version, upgrade to 22w17a, and the discounts no longer appear.

I am unsure whether this would be related to the UUID issue that has been already reported where all skins, advancements, etc. are reset in this snapshot.