Normally when you cure a villager, their major_positive gossip of the player that cured  should increase by 20, up to a maximum of 100. It should never decrease. A while ago I noticed all my villagers had increased prices, and using "/data get entity @e[type=villager,sort=nearest,limit=1] Gossips" I was able to confirm that my major_positive gossip indeed had reset.

While MC-251583 notes a bug where it only stores the major_positive gossip of the most recent player that cured them, this would not apply in my case.