Fenix Flexin is best known as a member of the Los Angeles rap group Shoreline Mafia. Recently, however, he achieved a breakthrough in his solo music career with the single “Rubberz,” which has climbed to No. 58 on the Billboard Hot 100.
However, almost immediately after the song went viral, questions arose about its origins, with many people speculating that it was largely—or even entirely—generated by AI. Fenix denied the allegations, but his response did little to dispel the doubts.
Some of the suspicion stems from the song’s dramatic stylistic shift. Fenix previously focused mainly on West Coast rap influenced by trap music, while “Rubberz” is clearly influenced by 1980s British synth-pop. The song’s vocal melodies noticeably evoke Morrissey, and Fenix even adopts something resembling a British accent.
Of course, musicians have every right to explore new directions and styles, and a change in style alone proves nothing.
More notable, however, is the quality of the recording itself. Careful listening reveals many anomalies and flaws commonly found in AI-generated music. For example, the hi-hat has a brittle quality, the chorus vocals sound like a low-bitrate MP3 file, and reverb tails are frequently cut off abruptly.
Charlie Harding, co-host of the Switched on Pop podcast and a songwriter, pointed out these suspicious details in an interview with The Verge. He said: “Ghostly backing vocals suddenly appear or disappear without rhyme or reason. The drum reverb is filled with unnatural digital distortion that recalls a 64kbps MP3 downloaded from Napster. Since most generative AI companies train their models on low-quality MP3s and unauthorized copyrighted material, we can hear instruments whose quality has been noticeably degraded.”
Running the song through AI music-detection tools does not provide conclusive evidence. Editors at The Verge tested it with five different tools, and the results indicated a 20% to 30% probability that the song was AI-generated or at least AI-assisted.
However, these detection tools are not necessarily reliable, and their development lags far behind the progress of AI music-generation models.
Some related materials did attract the attention of AI detection tools. For example, the single’s cover image and social media posts celebrating its success were each judged to be AI-generated by multiple AI image-detection tools, with confidence levels above 97%.
Similarly, the author submitted the lyrics to several AI text-detection tools and Gemini, all of which concluded that the lyrics displayed characteristics of AI authorship. Producer and YouTuber Curtiss King also entered the lyrics into Claude, which likewise identified multiple signs of suspected AI generation.
The lyrics exhibit a common AI trait: being “almost nonsensical from a logical perspective.” The rhyming is simple and direct, an approach unusual for a rapper who has already demonstrated a certain level of ability.
There is almost no slant rhyme or internal rhyme. Instead, the lyrics consistently use basic AA and BB rhyme schemes, clearly prioritizing the arrangement of end rhymes over actual meaning or narrative development.
For example:
“Swipin’ cards and stackin’ chips, I saw you sinkin’ ships”
“Left me standin’ in the pourin’ rain, now I bought a heavy diamond chain”
(Swiping cards and stacking chips, I saw you sinking ships.)
(You left me standing in the pouring rain; now I bought a heavy diamond chain.)
“Who is sinking ships? Are we the sinking ships?” This concept never appears again, and the lyrics do not develop it in any way.
Similarly, individual lines in the chorus appear meaningful, but together they lack logic:
“Bankrolls on the table”
“Watchin’ local cable”
“Hatin’ that I'm able”
“Hatin’ that I'm able”
(Cash sitting on the table.)
(Watching local television.)
(Hating that I’m able to do it.)
(Hating that I’m able to do it.)
Aside from the particularly awkward line “local cable,” the lyrics raise more questions: What exactly is Fenix able to do? Why does he hate that? The lyrics pose more questions than they answer.
The song’s vocal delivery is similarly strange.
The third verse seems to come to an abrupt halt at the line “Not the jewelry.” Harding believes the song “completely lacks flow.”
He said: “No rapper of even modest ability would deliver the title lyric, ‘I just let the rubber band snap,’ in this awkward way. Its rhythmic phrasing is extremely unusual, with all the accents falling in the wrong places.”
He further explained: “Because too many syllables have been crammed in, the song has to place the accent on the word ‘the’ rather than ‘rubber,’ causing all the subsequent syllables to be emphasized with an unnatural rhythm.”
The live “performances” of “Rubberz” did not seem to help Fenix escape the suspicion. During the first few studio performances, the rapper was found awkwardly lip-syncing. At times, the song’s strange rhythms and lyrics seemed difficult even for him to follow, as if he could not remember his own song.
In fact, he did not even appear to be trying hard enough to prove that he was actually singing the song.
When Fenix did genuinely sing, the problems became even more apparent. Multiple live videos show that he could not reproduce the vocal range and accent of the recording, and he also seemed unable to remember the lyrics. In many live clips, the original recording was still playing even while he was singing. His real vocals were turned down very low, while the DJ would deliberately lower the backing track briefly in an attempt to prove the song’s authenticity—but the results were unconvincing.
Fenix defended himself by saying that the differences between the recording and the live performances were mainly due to vocal-processing technologies such as Auto-Tune.
However, Harding, Curtiss King, and music critic Anthony Fantano, among others, all rejected this explanation.
King compared Auto-Tune to “a spell-checker.” Although Auto-Tune can indeed be used extremely heavily to create a distinctive robotic sound, its primary function is to correct pitch errors, not expand a singer’s vocal range or create a new accent.
Fantano pointed out that Auto-Tune cannot give a singer vocal abilities they did not originally possess.
Perhaps the strongest evidence that “Rubberz” was not AI-generated is precisely that it is “too bad to be AI.” Harding said: “I would assume that the person who made this song has never created music with anything beyond an ‘1980s children’s practice keyboard.’”
If the song was in fact made with generative AI, then it clearly used a relatively weak model.
He said: “What concerns me is that listeners would find a song made by some low-level generative AI music company using a poor model interesting. More advanced models have already made tremendous progress in reducing obvious audio flaws and improving strange vocal rhythms.”
Fenix has released clips that he claimed were Pro Tools session files, but this does not actually prove anything. Unless he publicly shares the original audio files and complete session files, doubts about whether “Rubberz” was AI-generated will likely never disappear.