CGI Tarkin had a lot more screen time and a much more prominent role. The CGI characters can’t act and they don’t coordinate very tiny muscle movements in the face right. When I saw the movie twice in theaters I too thought Leia looked much better, whereas Tarkin looked fake to me, but I think that’s probably just down to her barely getting on screen.
Even then, she looked more realistic but soulless. Kinda like you were looking at a picture of a dead woman from long ago when she was very young. And I thought that before everything happened with Carrie.
But it was still better than Tarkin. He just looked like a video game character to me.