In this spirit I've been playing with spun up Firefox instances in a Google Cloud Run. The container is stateless and goes away after I close the page that connects to video stream of the other container in my browser.
I'm assuming they want some protection against adtech companies or the local coffee shop sysadmin. Running Firefox in the cloud "to avoid detection by the NSA" would indeed be quite foolish.
Way back in 2009 I helped design and implement basically "Firefox on AWS EC2" - I had YouTube audio and "video" working, in the subwindow, not Fullscreen. It was roughly 5-10FPS, about what you'd get with VNC, with perfect audio.
I had an idea that thin clients were going to be big - and I stupidly pitched ideas for cloud based software to Adobe, Newtek, and Autodesk.