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Say (an encrypted) hello to a more private internet. | The Mozilla Blog
(blog.mozilla.org)
A place to discuss the news and latest developments on the open-source browser Firefox
HTTPS already prevents them from knowing exactly what content you’re looking at. Hiding SNI prevents them from knowing exactly what site you are connecting to via HTTPS.
They can still figure that out if you’re using unencrypted DNS or if there is a 1:1 IP to rDNS mapping though.