His headphones kept cutting out, so he read the AliExpress code

A developer discovered that AliExpress’s homepage creates two hidden WebAudio AudioContext objects that run a silent sawtooth-oscillator chain, forcing the browser to process audio and causing his multipoint Bluetooth headphones to drop the phone’s music stream. The scripts, identified as collina.js and fireyejs.js, collect extensive fingerprint data—including canvas, WebGL, device, and WebRTC information—and send it to Alibaba’s telemetry, while Firefox’s recent WebAudio fingerprint-mitigation limits the technique to a small subset of users.