"Pareto skewness" appears in https://hal.science/hal-00700465 (doi:10.1109/asonam.2012.91) from 2012, though I'm not sure whether it has the same sense. Unfortunately, https://forum.earlyretirementextreme.com/viewtopic.php?t=319... from 2013 is a perfect match:

> Etsy seems dominated by stores that sell nothing with a few that do rather well. It's severely Pareto skewed.

This is a relatively rare use of language, so you might deserve co-invention credit.