OK THAT is kind of bizarre. I picked mine up 11/22 - ordered on 10/22 and mine works across the entire strip.Just chiming in on this thread as I picked up a new 2021 JULR last week.
One thing I checked right away was this defrost issue. Sure enough, heat blasts out of the center like there's no tomorrow but next to nothing on the edges of the defrost panel on the driver or passenger side. And sure enough, when you put something over those middle holes, it forces more out out the sides.
Blows my mind that Jeep has not addressed this issue when it goes back years and so many people have complained about it in this thread. There's no way they aren't aware of the problem.
Sadly, it'll probably take a major accident and some kind of lawsuit before they fix the problem.
I've purchased these socket rail plugs which seem like they'll work pretty well.
Will probably watch this thread for other solutions.