What happened
On September 9 Suno began moving its whole service to v6: three models, with v6 and v6-wild for Pro and Premier subscribers and v6-mini for everyone, which chief executive Mikey Shulman described as developed with industry partners including Warner Music Group, BMG and Believe. Earlier models are being retired as it rolls out.
On September 18, Universal Music Group and Sony Music Entertainment, with Capitol Records and nine Sony labels, filed a second complaint in federal court in Massachusetts. It lists 60,202 recordings, alleges Suno stream-ripped many of them from YouTube in breach of the Copyright Act's anti-circumvention rules, and seeks up to $150,000 per work infringed. The case the same labels brought in 2024 is still in discovery before the same court.
The interesting bit
The new complaint is less about what v6 was trained on than about what trained it. It alleges Suno used users' preferences between pairs of songs made by the old models, and knowledge distillation—a “student” model learning the behaviour of “teacher” models, here Suno's own unlicensed predecessors. Training on those outputs, the labels argue, does not end the infringement but launders it; v6, the complaint says, is “the fruit of the same poisoned tree.”
If a court accepts that, retiring a model is not a reset: whatever it learned from unlicensed music would travel with every model that learns from it. Nothing has been decided. Suno has not yet answered the new complaint, and in the 2024 case it argues that its training was fair use.