Copyright covers creative expression, not functionality. The code and unique design elements would be protected, but not the idea of a grid or guessing letters, etc (which all predate them anyway). Even the word list is difficult to claim protection to if it was generated by algorithmic filters on dictionary words (it probably was) because then the selection also isn't expressive.

So I can't copy their code or exact look, but I can definitely make my own version legally.

What's the point? Yeah I don't know why they spent money on such a simple concept either. The copyright protection is far more useful when the thing has enough expression that clones won't be indistinguishable anymore.

Which is why we're in this shitty timeline where every creative project is being handled by people that do not create. A lot of artists worked on a movie, but because soulless executives had all the money to own creative rights despite having no part in the movie's creation, they just got rid of the movie to save on taxes. Creative ownership should never be decided by money.