If you only inject your fingerprint spoofing scripts via `Page.addScriptToEvaluateOnNewDocument`, those hooks only run on the **main window thread**! When an anti-bot script spawns a `new Worker(blobUrl)` or `SharedWorker`, the worker thread reads the raw unpatched `WorkerNavigator` (`navigator.userAgentData`, `navigator.hardwareConcurrency`, `navigator.platform`) and catches your lie! Use CDP `Target.setAutoAttach({autoAttach: true, waitForDebuggerOnStart: true, flatten: true})` to intercept and patch Worker targets before their first line of JS executes!