I think in this case the concept is that you are sending a thank you to Kamala Harris? So it’s supposed to make you feel like you will be contacting her directly in some roundabout way. So in that case although the text is to you, the thank you they are requesting you sign is to Kamala Harris.
The picture is a screenshot of a recent viral video where a woman was being street interviewed and she referred to giving a sloppy bj. She said “hawk tuah” as the onomatopoeia for spitting and it became a a meme. In this picture they replaced the “tuah” with “tui” for text user interface. Hawk is a kind of bird. So the meme reads “hawk tui” is the name of their bird based text interface.