alt Hacker News>Both Google Chrome and Microsoft Edge actually implement this. [...] both will upload your browser history to the cloud.
I'm fairly certain I've caught Firefox doing something similar (regularly sending multiple tens of MB to Google servers in the background.)
So fwiw, browsing history shouldn’t be anywhere near that big making it unlikely there what it was. It compresses well, if they were to do it I’m sure they’d do it at regular intervals instead of a years’ worth at a time, etc.
And, of course, Firefox is open source and this wouldn’t be kept a secret.