Billboard Hot 100 hit 'Rubberz' sparks AI-generated speculation

Fenix Flexin, best known as a member of Los Angeles rap duo Shoreline Mafia, has found solo success with the song 'Rubberz,' which reached number 58 on the Billboard Hot 100. Almost immediately, listeners and experts began speculating that the track was predominantly AI-generated. Fenix has denied these accusations, but his responses have done little to quell the doubts.

One reason for suspicion is the song's radical departure from his usual style. Fenix has built his career on trap-influenced West Coast rap, yet 'Rubberz' is steeped in 1980s UK synth-pop, complete with a vocal melody reminiscent of Morrissey and a fake British accent. While artistic evolution is normal, the recording's audio quality raises further red flags. Close listening reveals brittle hi-hats, chorus vocals that sound like a low-bitrate MP3, and reverb tails that cut off abruptly.

Charlie Harding, a songwriter and co-host of the Switched on Pop podcast, pointed out ghostly backing vocals that duck in and out unexpectedly, and drum reverb full of unnatural digital artifacting, akin to a 64kbps MP3 downloaded from Napster. He suggested that many AI music companies train their models on low-quality, unlicensed copyrighted MP3s, resulting in audibly degraded instrumentation.

The lyrics also trip up AI detectors. Multiple AI writing detectors and Gemini flagged the lyrics as AI-written, and producer Curtiss King found similar signs using Claude. The rhymes adhere to a basic AA, BB scheme, favoring simple and clean rhyme pairs over meaning or narrative. Lines like 'Swipin' cards and stackin' chips, I saw you sinkin' ships' raise questions that are never answered, and the chorus's individual lines do not connect logically.

The delivery is equally odd. Verse three ends mid-thought on 'Not the jewelry,' and Harding noted a complete lack of flow. He argued that no half-competent rapper would sing the title line 'I just let the rubber band snap' with such awkward syncopation, emphasizing the wrong syllables. Live performances have compounded the issue, with Fenix awkwardly lip-syncing and being unable to replicate the vocal range and British accent. Even when he attempts to sing, the original vocals are played over his own, and his real voice is nearly inaudible.

Fenix attributes the difference to vocal processing and AutoTune, but experts like Harding, King, and Anthony Fantano dispute this. AutoTune can clean up errors or create robotic textures, but it cannot extend a performer's range or introduce an accent.

Running the song through several AI music detectors gave only a 20–30% probability of AI involvement, but image detectors flagged the single's cover art and a celebratory post as AI-generated with over 97% certainty. Fenix has shared Pro Tools session files, but they do not prove authenticity. As Harding noted, the song sounds like it was written by someone who never used an '80s kids practice keyboard, possibly from an inferior AI model. Without releasing the original recording and project files, Fenix may never shake off the AI allegations.