After defeating a raid, the lower trade prices are revealed by the villagers. However, after trading 2 or 3 times, or removing untraded resources, these remaining resources will disappear, often matching the original trade price. It appears the effect does not fully go through and the villagers end up trading for full value.

• also the version should the newest update; 1.14 (not 1.11.2), but that is not an option in the drop down menu.