If I go to a concert, I expect to hear the singers singing and instruments playing live, not miming to a recorded track. I know that Taylor writes, or is at least involved in creating, her songs, and I respect her determination to own the music she created.
The concert tour, however, is an expensive fraud. And if you talk to professional singers, they will tell you that it is ridiculous to expect anyone to sing for so long, so frequently. The human voice just can’t maintain that.
It’s not too surprising that Taylor does it. Far more shocking to me was proof (on the same YouTube channel) that Cliff Richard and Roger Waters also lip sync and have been doing it for many years.