Rex render in general needs work, she's still the doofy looking one from the last one from what I can tell, but it looks better than the art the used for the first World merch yeah.
So, with JW they didn't have ILM renders cooked up for the merch.. Universal did a solicit to do them for later waves, but changed their minds. That's why all the renders were sooo damn goofy - they were from early unfinished ILM meshes, and they had to be painted up.
This time, they had ILM render these, and they're from the film assets. I first saw these new renders back in May, but I do believe they have existed before that.. from my understanding, the newer dinos will appear in later 'waves' of promo material.
As for the Rex, she looks goofy simply because they fucked her up in JW and are retaining the look. It's unfortunate. She lost a lot of her hard angles, and everything has been rounded, giving her a very different, cartoony look.