I looked back and honestly it's not like completely noticeable. Or at least I didn't notice it that much until after reading your comment lol.
Think it's more so the rendering/shading that changed. The artists linework had always had that crispy sketchy style to it, though recently there is definitely more detail (especially in the hair). In the newer style, there seems to be more cell shading rather than full on rendering

I just started reading and the art difference between chapter 1 and 20+ is kinda abrupt. How did the artist improve so fast? Share the secrets woah