Speculation that the former One Direction frontman uses the app began swirling last month, when the star was paparazzi'ed holding an unlocked iPhone.
Savvy netizens quickly zoomed in on his phone screen, which appears to show a TikTok account with two uploaded videos. Not even the power of Photoshop could make the username on Styles's screen legible, though.
To quote Kris Jenner: "This is a case for the FBI!"
Somehow, TikTok-ers uncovered an anonymous account by the name of @suemonella. Drawing parallels between mysterious videos posted to the account and Styles's personal life, fans are convinced that @suemonella is Harry in disguise.
Let's start with the username, which reads as a mash-up of "Sue" and "salmonella." As some very astute fans have pointed out, Harry Lambert — Styles's stylist and close friend — often refers to the singer as Sue on Instagram. (No word on where salmonella comes in, though.)
There's also the content posted to @suemonella, a total of six clips including a shot of someone's jogging feet set to "Unwritten" by Natasha Bedingfield, a fruit bowl, and more feet, this time walking up pink stairs. Pretty mundane, but wait! Styles has pink stairs in his house!
There are a couple of other smoking guns — or red herrings, depending on who you ask.
There's a clip of Wolf Alice, who happens to be opening for Styles on his European tour. And there are two videos of a silver Spotify plaque commemorating 1,000,000,000 streams. If you look closely, you can catch "Harry Styles - Watermelon Sugar" on the lower half of the award.
Pretty convincing, though I have trouble imagining Styles captioning his first post: "First tick tock [sic] reminds me of vine."