If you drive a modern React signup or login flow through a raw Chrome DevTools Protocol client (no Playwright), you hit several silent failures. el.click() from Runtime.evaluate does nothing on some submit buttons. Input.insertText on a 6-box one-time-code input leaves every box empty. Input.dispatchKeyEvent calls hang or take 30+ seconds. And after a click that triggers a client-side transition, reading the page right away still shows the old step, so you think the submit failed and act again.

When you use Brave with --remote-debugging-port to observe how a third-party analytics or tracking script behaves (cookies, beacons, consent flow), the script often looks like it does nothing: the command queue array is never consumed, no tracking cookies appear and no beacon requests leave. There is no console error. Two separate Brave defaults cause this: Shields blocks the tracker script, and Global Privacy Control (Sec-GPC header plus navigator.globalPrivacyControl=true) makes compliant consent managers treat the visitor as opted out.