[1101010010]

https://browserleaks.com/canvas

Open it in a regular and "incognito" browser tab. This is a long term identifier of your browser which persists across cookie clearing, IP address changes and other ritualistic totems privacy-seeking individuals still inexplicably cling to.

[hosteur]

How do one protect against this?

[coldblues]

https://support.mozilla.org/en-US/kb/firefox-protection-agai...

[1101010010]

Simply don't allow Javascript.

[trh0awayman]

Unfortunately, even that might not be enough these days with newer fingerprinting methods.