OP, I can see you know how to get information out of the NPCs.
I did actually check the NPC when I first saw your message, and then again a few days later when I posted, and I believe the NPC was indeed changed in those few days. These big jump discontinuities (cliffs) are real in the NPC, and presumably in their actual formulas. Most elite/generous colleges I have checked, even if they advertise certain aid below certain income level (with typical assets), do not have such big (or any) jumps, because their formulas are on a gliding scale, and the promises at certain income level simply advertise what their formulas already deliver at those income levels. But I did also encounter big cliffs on some NPCs.
I definitely agree that you want assurance that a college will stay affordable for 4 years. UChicago is definitely an elite, wealthy, generous college, but I’d be concerned that its finaid seems somewhat shakier than that of its peers. (Our kids didn’t/won’t apply, but for other reasons such as not good fit, and little chance of admission anyway.)
For our S24, for the somewhat elite colleges where he was accepted, the NPCs were very close to the actual finaid offers, (except or one that includes 100% of house in assets, so avoid such schools because you can’t control what value they use). Where S24 went, entering 3rd year, the NPC continues to be totally accurate.