A Taylor Swift fan recently served up a ‘6.21’ theory, sharing an Eras Tour video in which they believe numbers are repeated in the lighting. Listening to the music is the biggest part of being a Swiftie, but remaining eagle-eyed and vigilant when it comes to the visuals is part and parcel of the fandom. Costumes, social media posts, and choreography at the shows—Taylor Swift’s fans are always on the lookout for the deeper meanings embedded within. Meanings that could tease something big on the horizon. Since the Eras Tour began, fans have been quick to raise their theories, compelled to belie…