Starting with 1.20.2, this bug no longer applies as villagers can no longer get better discounts when cured multiple times.
Updated the bug because the previous description was incomplete
Can reproduce in 1.16.1
This is still an issue in 1.16 rc1. I updated the affected versions to reflect this.
Gavin Dimp
Starting with 1.20.2, this bug no longer applies as villagers can no longer get better discounts when cured multiple times.