Did an AI Music App Just Snitch on the Song of the Summer?

There is no such thing as a universal “song of the summer” anymore, but if you’re into rap music, Fenix Flexin’s “Rubberz” is a pretty strong contender. Officially released in June, it currently sits at #58 in the Billboard Hot 100 and has a music video with 7 million views. Lyrically, it’s got everything you’d want: boasts about cash and jewelry, and bars that work as a double entendre for braggadocio and depression. But there are two interesting twists to “Rubberz.” First, it isn’t a rap song at all; it’s a synth-pop tune that would be at home in a moody ‘80s playlist. Also, since it dropped, it’s been the focus of accusations that it was completely or partially AI-generated. The argument reached a peak this weekend after an independent music producer claimed he’d figured out not only how Fenix had made “Rubberz,” but that the rapper’s labelmate, Tyga, also seems to have used a little-known generative AI music app to create some ‘80s-themed tunes of his own. And now, the creators of that same AI music app have effectively snitched on both: the service’s new built-in detector is now flagging the songs made by both Fenix and Tyga as likely AI generated. This may finally settle the argument fans have been having all summer. It won’t settle the one they’re about to start. Tune Up People were suspicious of Fenix from the beginning; “Rubberz” is not only an unusual genre shift for the artist, it also doesn’t sound like his voice in the song. Fenix Flexin grew up in East Hollywood and he sounds like it, and when he first debuted as part of the group Shoreline Mafia in the late 2010s, you could always recognize which bars were his because of his somewhat nasally, congested voice. The voice on his June 5 release of “Rubberz,” however, is completely unrecognizable. It’s a lot brighter and crisper, and the accent sounds closer to a very chipper Morrissey. Both he and the credited producer, Purps on the Beat, have denied using AI at every turn. Fenix told Channel 5 that he “freestyled” the lyrics, and in the comments of an On the Radar performance, he replied to people accusing him of using AI: "No sirrrrrrr, recorded same as all music I do! Only difference is auto-tune reverb and me using my fake uk accent lol." Not everyone bought his explanation, but there was no proof otherwise. As the summer continued, music media debated whether “Rubberz” had been AI-generated. But none of the well-known AI music detectors flagged it, Fenix denied it, and the song continued to rack up plays. Fans had no choice but to get comfortable with the question being unresolved. Then, things shifted suddenly. On Thursday, a music producer named Medasin posted a video claiming he’d figured out how Fenix used AI to make the track. It wasn’t Suno, or Udio, the two most prominent generative AI tools for making music. Instead, Medasin says, Flexin had used a lesser-known app called Treblo. Medasin breaks down his accusation methodically: first, he points out that the app used to be called Sonauto until two days before “Rubberz” was released. And then he shows a screencap of one of Fenix’s old Instagram Stories teasing his new ‘80s sound. A freeze-frame and zoom reveals that a filename being shown on screen has the suffix “Sonauto.mp3.” But the most compelling accusation comes when Medasin shows how he was able to use Treblo to create a very similar track. By using tags like “80s synthwave” and prompting the app to write lyrics about a “rapper lifestyle,” Medasin got a similar-sounding song. The lyrics even bear more than a passing resemblance to “Rubberz.” For example, Medasin’s prompt got him the lyrics “Diamond chains hanging heavy”; “Rubberz”’ has “Now I bought a heavy diamond chain.” Medasin’s generated song gave him “I see your face in the champagne bubbles”; Fenix’ song has “Still seeing your face in the glass.” Both songs feature some permutation of “pockets thick,” both mention “plastic smiles.” “There's just way too many coincidences,” Medasin said in an interview with WIRED. “It is just a mathematical impossibility that he did not use Treblo.” This all made me curious, though. Would Treblo allow me to recreate a “Rubberz”-style song? It turns out: yes. By entering tags like “80s synthwave” and asking it to make rap lyrics, I got not only a similar sound, but similar lyrical structures. In my first try, I generated a song (you can hear it here) with the couplet “Rings on every finger / Leather seats and cedar scent linger,” an almost mirror duplicate of the “Rubberz” line “Gold rings on my fingers / Still your perfume lingers.” I continued to generate songs. Even with slight variations, any time I combined an “80s” tag with a prompt for “rap lyrics,” I got similar results. Whereas ChatGPT seems to like goblins, em dashes, and “It’s not X, it’s Y” constructions, Treblo’s engine seems to be obsessed with “finger/linger” rhyme pairs, talking about rings and glass and pockets, and song constructions in which there is a thematic transition from night into day. Medasin says his Treblo revelation happened a month ago, but he kept it quiet; he figured some journalist would do the legwork of connecting the dots for the public. This did happen on a smaller scale, perhaps most thoroughly on an AI music news site called Zinstrel, but it never really broke through. Medasin’s video was the first to capture attention. As Thursday went on, it seemed that Medasin had struck a nerve with his video accusation. That afternoon, Fenix posted a video on his Instagram page of what he said was the original project file for “Rubberz.” If authentic, this would serve as proof that the song was not AI; that “Rubberz” had been created from scratch in a studio. But music producers immediately jumped into the comments, with many claiming that the project file being shown looked suspiciously like someone had just taken an existing song and used a “stem separator” to extract a full song into rudimentary components like bass and drums; which would point back to it just being an AI song that they couldn’t create. Hours later, Fenix deleted the post. Neither he nor Purps On The Beat have addressed the “evidence” video since, or why it was taken down. Requests for comment sent to both by WIRED went unanswered. Then, another one. Two days later on Saturday, Medasin dropped another video, this time alleging that Tyga’s new $TARFACE project is also at least partially using Treblo. He starts with some loose connections: videos were posted on social media of Tyga and Fenix together, both are on the same label, the same sudden rapper-to-80s crooner pathway. But also, he ran a Tyga song in a new AI music detector a friend is developing, and it was flagged as AI. But it’s more convincing to hear directly from Treblo itself. "Someone appears to have used our model to find a sound that millions of people connected with,” Treblo cofounder Ryan Tremblay said when asked for comment, “and that's exciting.” Treblo had not previously spoken to Tyga or Fenix, Tremblay says, and the company wasn’t “even aware [“Rubberz”] existed until after it hit the Hot 100.” Asking Treblo about individual songs might not be necessary in the future. Late Sunday night, Treblo published a page titled “Was This Made With Treblo?” In short, it’s a Treblo music detector. “We also think listeners should know what they're hearing,” a blog post explains, and describes it as a tool that is “tuned to detect songs made with Treblo with little to no modification.” Sure enough, feeding “Rubberz” into the tool returns a result of “Very likely Treblo.” Running a track that Tyga dropped in early July returns a result of “Likely Treblo.” The rate of false positives, Treblo’s site says, is under one in ten thousand; a fraction of a percent. The detector’s efficacy has not been independently reviewed, but Treblo has released the code under an open source license so anyone can inspect it and test it. Requests sent by WIRED to Tyga’s label for comment were not returned. Slop or Not The timing of all this coincides with a trend of platforms making gestures toward AI-generated content. The same day that Medasin posted his first video, LinkedIn rolled out a new feature: a “seems like AI” button that allows users to flag AI slop in posts. Two weeks ago, Substack released a new feature that purports to detect AI-written newsletters. Tidal has blocked monetization of AI-generated music, and while Spotify doesn’t have an AI tagging feature, there’s a crowdsourced tracker where you can report slop to other listeners. The proliferation of image and video generators over the last few years has provoked worries about the spread of machine-made content and misinformation. A bipartisan AI Labeling Act in the US Senate has been suggested as a partial solution: forcing platforms to visibly label AI-generated content so that it would be clear whether online content is real or not. “People deserve to know,” one senator told Politico. What we should have anticipated was that there would be people who don’t want to know. People who would get angry if you ruin the fantasy. The comment section of Medasin’s first video is full of this: people who say they like “Rubberz” anyway, that they don’t care that the song is AI. That AI is the future, and that Medasin is just jealous that Fenix thought of it first. Medasin says he wasn’t surprised by the reaction. He admits he liked the song when he first heard it, and still somewhat enjoys it in an ironic sort of way. “It's catchy, and it was stuck in my head for a fucking month,” he says. So why risk a bunch of people looking at him like he’s the guy in the conspiracy board meme? Ultimately, Medasin says, he thinks there can be a place for AI in music, even if he doesn’t like it personally. But he wants artists to tell the truth, so listeners can decide for themselves. “This is, like, a critical moment in music history,” Medasin tells WIRED, “And I have very, very deep respect and love for the journey of musicians and humans and human experience being celebrated and present in music.” He decries anyone who would be deceptive about that and profit off of it. “It is unethical to me on a very spiritual level,” he says. Music fans spent half the summer arguing over whether a surprise hit song was synthetic. It looks like they have an answer. Now they just have to decide how much it matters to them.