Did you know? Despite claiming to block all cross-site cookies out of the box, Firefox automatically allows Google to use them in your browser should you log in to one of their services.
The browser only lets you know about this once it happens, and it’s on you to notice the permissions icon appearing in the URL bar. There is a link to a paragraph on a help page explaining this behaviour, but it seemingly goes unmentioned pretty much everywhere else on the internet.
This surprised me, especially considering Firefox’s stance on privacy. I was even more surprised that this is done without consent. If this is for usability, Firefox should at least warn the user before this happens.
If you access Google sites only in a special Firefox container, that still isolates your Google cookies from the rest of your tabs? Or does it just add a “you don’t get this from me” flag when it gives Google your user cookie, so it can pretend to not recognise you as it adds your web-browsing history to your ad-targeting profile (flagged appropriately as to keep it deniable, of course)?
Yes.
I have a google container for one account.
If I open a google site in another container it will be as if the account didn’t exist.
The containers are all partitioned.
You can also partition off the cookie/storage per site by proxy used (in about:config).
So, you could create a container for google account 1 using proxy 1 and another container for google account 2 using proxy 2 and they will never have access to the data stored by either.
Out of curiosity, do you know if these containers also obfuscate browser and device fingerprinting? Separating cookies is important but unless it also blocks fingerprinters (in a different way for each container) the site will instantly know the same person is using both accounts.