Fenix Flexin Effectively Admits AI Made 'Rubberz' After Treblo Detector Confirmed It

LA rapper Fenix Flexin has stopped denying that AI generated his Billboard Hot 100 single "Rubberz," effectively conceding what Treblo's open-source music classifier already confirmed: the 80s synth-pop track was made with an AI tool.

Key takeaways

• Fenix Flexin's "Rubberz" reached #58 on the Billboard Hot 100 while listeners and the music industry debated whether it was AI-generated.
• Producer Medasin publicly claimed the song was made with Treblo (formerly Sonauto), an AI music generation platform.
• Treblo released an open-source AI detector that identified "Rubberz" as generated by its own tool — providing technical confirmation.
• Flexin previously said AI had "nothing to do with the recording process"; he has since replied to posts saying he "never said I didn't use AI."
• Major labels have separately proposed banning AI-generated tracks from chart eligibility, making this case a live test of that debate.

From flat denial to quiet reversal

The story moved in stages. Flexin initially deflected, telling fans the song had "nothing to do w recording process" and that he "didn't even know what da app was." That framing — AI touched the production, not the recording — gave him a narrow exit. But according to The Verge, he has now replied to posts pushing him to admit AI involvement by saying he "never said I didn't use AI" — a phrasing that closes off the denial without quite being a confession.

The technical case was already settled. Treblo released an open-source classifier trained to detect songs made with its own generator, and it flagged "Rubberz" as a match — a self-incriminating move that gave the story its hard evidence. Producer Medasin had posted videos making the same claim, but a developer's accusation and a detector built by the accused tool's own company carry different weight.

What the chart placement actually means

"Rubberz" hitting #58 on the Hot 100 is the reason this case matters beyond rap gossip. A fully AI-generated track — if that's what it is — charting inside the top 60 is the first clear real-world test of a question the industry has been arguing about in the abstract. Universal Music Group, Sony Music, and Warner Music Group have proposed stripping AI-generated songs of chart eligibility entirely, and "Rubberz" is now the obvious exhibit A in that debate.

For creators working in AI music tools — or experimenting with AI-assisted production alongside human performance — the line Flexin tried to draw (AI in the production chain, human in the recording booth) is exactly the distinction the labels' proposal would need to define. If chart rules eventually require disclosure or ban AI-generated stems outright, every producer using tools like Treblo, Suno, or Udio will need to know where that line sits. Suno has already moved toward watermarking AI-generated audio and capping downloads to address abuse; Treblo's self-detection tool points toward a future where AI provenance is technically verifiable whether artists disclose it or not.

The detector as the new normal

The most consequential part of this story isn't the rapper — it's the precedent set by Treblo releasing a classifier that can identify its own output. That's a meaningful shift. Once AI music platforms routinely embed detectable signatures in their output (voluntarily or under regulatory pressure), the "I didn't know what the app was" defense evaporates.

Creators who use AI-generation tools for music, images, or video should assume that provenance detection is coming to every medium. The EU AI Act's transparency rules, now in force, already require disclosure of AI-generated content in regulated contexts — a legal layer that sits on top of the technical one. The Flexin case illustrates how quickly a soft denial collapses when the tool that made the content can identify itself.