Taylor Swift has surprised fans once again by releasing a brand-new song "from the vault" unannounced! On Wednesday, Swift dropped the previously unheard track "Mr. Perfectly Fine (Taylor's Version)," and there's already speculation when it comes to who she's singing about!

Swift originally wrote "Mr. Perfectly Fine" back in 2008

Swift's latest song "Mr. Perfectly Fine" is one of the six bonus tracks to be featured on the upcoming rerelease of her 2009 album Fearless. Last year, the singer began the process of re-recording her old catalogue of songs, and recently shared that Fearless (Taylor's Version) will be available on April 9.

Her decision to spontaneously drop "Mr. Perfectly Fine" on Wednesday comes just a couple weeks after she released her first song "from the vault". But while the Maren Morris feature "You All Over Me" has a distinctly country sound to it, "Mr. Perfectly Fine" is more of an uptempo, pop track! 

Taylor Swift at the 55th Academy of Country Music Awards on September 16, 2020, in Nashville, Tennessee.

Swift's new song is supposedly about ex-boyfriend Joe Jonas

Swift took to Twitter to comment on "Mr. Perfectly Fine" when she released it! While she said that she's been "writing songs based in fiction to avoid drama, feeling pretty grown up," she joked that her "2008 music from the vault, in a goblin voice" told her to drop the song!

The internet rumour mill has suggested that "Mr. Perfectly Fine" is about her ex-boyfriend Joe Jonas, who she dated back in 2008. Since the timeline of their relationship lines up with when Swift wrote songs for Fearless, the possibility of Jonas being the song's titular "Mr." is perfectly reasonable!

Also contributing to the speculation is the fact that Jonas's wife, Sophie Turner, took to her Instagram Story to comment on "Mr. Perfectly Fine"! "It's not NOT a bop," Turner captioned her post. Swift then reposted her comment with a Game of Thrones reference, saying she's "forever bending the knee" to the actress, who played "Sansa Stark" in the hit HBO fantasy series.

Taylor Swift's repost of Sophie Turner's Instagram Story on April 7, 2021.

Listen to Taylor Swift's new song "Mr. Perfectly Fine (Taylor's Version)" here!