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.
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.
FF doesn’t really enable full fingerprint resistance by default. But it can.
These settings are some of what I usually use. All fingerprint values (that are able to be are randomised on every reload of a page.
Set secutity setting to custom, select known AND suspected fingerprinting > select from dropdown ‘In ALL tabs’
Also: Because it’s of no value / use to me, and (IMHO) a giant gaping privacy and security issue, I also disable webgl and webrtc, and navigator completely in about:config
Set the following:
WebGL webgl.disabled true
WebGL2 webgl.enable-webgl2 false
WebRTC media.peerconnection.enabled false
Navigator media.navigator.enabled false
RFP privacy.resistFingerprinting true
RFP options like bounce protection etc can also be enabled in config.
Check fingerprints on browserleaks.com, coveryourtracks.EFF.org, etc
Should be 100% unique fingerprint every time.