Read this on the Northridge 4x4 website.....
"Jeep had a brilliant idea to make the JL frame rails out of a new harder material, but trail testing has exposed a major flaw: thinner walls but stronger material twists! Early in 2018's Easter Jeep Safari exposed major flexing and twisting in rigs coming back off their day's runs."
it's and excerpt from here...https://www.rockhard4x4.com/product_p/rh-90509.htm
In this youtube link, frame twist is again mentioned.... This and the frame weld issues that are well reported has got me a little worried. I just ordered a '19 Rubicon.
its a commercial