Since Snapshot 22w12a Piglins barter every 121gt instead of every 120gt like it used to be before. The cause of this issue is the same change in the brain class which caused the bug that villagers spawn iron golems every 35 seconds instead of every 30 seconds (MC-254100 also has further explanation in a comment). There are also more mobs that go through that class and might also have weird behavior beeing caused by that change so it needs further investigation.

 Thanks to skyrising for code analysis that is attatched.