The new grille and headlight treatment are very similar to the latest Sonata and new, larger 2021 Elantra sedan (in NA markets). No doubt they're trying to come up with some sort of design 'continuity' acros their lineup but not sure how much I actually like it at this point? I've seen a new Sonata in the flesh and thought it was a bit odd. The whole car was almost cartoony in a way? Not sure if that is the right word, maybe 'overly bold' is better? Seems like they are trying a bit too much to make their cars stand out from other carmakers. Better the clean and classy direction as I'm not sure these new updates will age all that well. I agree that the initial 2017-2020 PD i30/Elantra GT is overall quite a handsome design, one reason I bought one.
Another thing on all three that I'm not all that fond of is that the instruments are now no longer physical and instead wholly digital representations. This is general trend in automotive instrument panel design (started I think by BMW?) that does not appeal to me - they're never really crisp enough and look too flat versus the real thing. I also prefer the layout and shape of the earlier (2018-2019) i30/Elantra GT gauge cluster with the tach and speedo on either side and both the same diameter and shape. To me that layout is far more balanced and cleaner compared to the facelifted version.