> design is supposed to be invisible

I don't know who told you that but that's a terrible take. Design can have personality. Design can convey emotions. Design can give you emotions and reactions by itself.

Not everything needs to be bland like a user manual

I edited above. I didn't recall the statement correct - design elements are supposed invisible even design itself is noticeable as a feeling or personality or aesthetic. But I think in this case, what hits users is the elements - the huge text, reverse text and black box.