I don't remember how my 2020 was before I put the airbags in, I put them on pretty early into owning the truck (around 1000 miles on the truck I think). So I can't remember if there was this much noticeable squat before the airbags. I do know that with the airbags, it made a big difference when pulling a trailer and rear end squat overall. I do at times have 500+ lbs over metal coil material in the bed of my truck, so I would have noticed I think if my 2020 squatted badly pre airbags. And I feel like my 23 AT4X squats more than my 2020 AT4 ever did when pulling a trailer before the airbags. It just has more give in the rear, period.
If it were me - I think the least expensive "fix" is airbags. I wouldn't mess with the front, you've already got it leveled. I know there are some helper type of springs (someone linked them on this site somewhere) you can clamp onto the rear leaf springs, but they cost more than airbags, and I have not had any experience with those to guage how much difference they would make. I have considered them, but since they cost more than the airbags, and I already know I liked having airbags on my 2020, that is the option I would choose.
Maybe others will have options I haven't thought