I think she uses a prompter because she never sings her songs live exactly the way they are recorded. Some verses and Corus repititions are taken out and remixed in a different way for the show. I don't blame her. I would have been singing the wrong part at the wrong time LOL
It’s common for artists to have teleprompters. As a backup in case they forget a line or get distracted with all that’s going on. Some are more discreet. It’s not like they are staring at the words the entire time.