You may be expecting the "Shake It Off" singer appeared in a background role, a secretive cameo or a deleted scene. That would make sense, being as her good friend Selena Gomez is the show's executive producer. However, as Teen Vogue pointed out, it's something completely different.
Tumblr user shakeitoff6202, a teenage "Swiftie" from Scotland, noticed that in the background of episode 10 ("Tape 5, Side B") Swift's figure is seen on a bulletin board in Liberty High School.
Furthermore, it's the famous shot of Swift on her revered 1989 album that came out in 2014.
In the scene, Tyler is shown talking to Sheri in the hallway in front an art class bulletin board. Peering between the two is a drawing of Swift's album cover.
Many fans have pointed out that Swift recently made a similar poster cameo in Gomez's "Bad Liar" music video, so this could be another version of that type of appearance.
While it's no stretch to see Gomez slipping the nod to her pal in the background of the scene, it's more likely a less cool explanation.
Logically, the nod was probably put into place by a set dresser or designer. Swift is one of the biggest stars in the world, so it's super believable that a high school student would draw her for a project. Furthermore, it helps the show feel more rooted in the real world.