FWIW, I happened to try and login to my Google account a few months ago and was promptly kicked out in exactly the same way, and after root-causing "what did I

FWIW, I happened to try and login to my Google account a few months ago and was promptly kicked out in exactly the same way, and after root-causing "what did I do..." I realized it was because I'd just set --remote-debugging-port=.... when restarting my Chrome session. Turns out this sets navigator.webdriver (as in, makes that key exist), which Google's login chucks a wobbly at. It will not let you in with that set, sadly because dumb scammers seem to absolutely love (???) using headless Chromium to attempt to fulfill their dastardly plans. (Which is really sad, because it makes legitimate tinkering that much harder (eg, can't interact with my primary session using nodejs/whatever :<).) I'm wondering if Firefox is setting something off something similar. You say this only happens randomly? I wonder what correlated thing is happening at the same time as these failures, and if the "oh it's that" is on your or Google's side of the internet connection...