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 No. 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 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 screen cap 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.”