Maybe check out Matt McManus’s work, he’s a professor at the University of Michigan.
You aren’t accounting for the increase in cool stuff that makes people want to stick around longer. There’s at least one more Dune movie coming and even a Rebel Moon for the Snyder people. When dueling was popular people were going to church for fun… If you believe in an afterlife and most of your time is spent peasanting about, why not have some fun in a duel?
https://digitallibrary.un.org/record/1629536?v=pdf UN report from 2018 so pre-pandemic.