I think it's not impossible they may store fat, but may be not this hilariously chonky.

Yeah, i assume so too, but i'm not sure if the specific way of storing fat is accurate, yk? I believe reptiles and mammals store it in different ways but i don't know the specifics, hence i'm asking this question here.

Its limbs look like twigs.

From a quick Googling, it's pretty much reptiles store fats in belly and tail, and we actually saw depictions of Hadrosaurs with a thicc af tail and big hind torso, surprisingly depicted the "fat storing" thing more accurate. Those depictions go well with the fact that Hadrosaurs had strong tails and hind legs for balancing, so possibly their weight and fat were more focused to the hind part of their body. This depiction, however, I think the front torso is a little too big and it's not just wrong with what I googled but also the anatomy of the animal. Those poor front limbs may not be able to handle such weight.

Why thank you kind individual for providing such a detailed answer! Kinda curious now how that would differ from species living more in the north like Edmontosaurus annectens vs. species that dwelled more in the south like Gryposaurus.

^ The Maastrichtian Stage had way less climate variation than we do. The Equator and North Pole likely had less than a few degrees of difference in Summer.

^Oh yeah, that's true, forgot about that. Still, maybe they could have bulked up for winter? But i digress.

I vibe with the idea of a chonky hadrosaur, but I wouldn't say that they would be THIS chonky.