https://www.bleepingcomputer.com/news/security/mozilla-starts-rolling-out-site-isolation-to-all-firefox-channels/ > Mozilla has started rolling out the Site Isolation security feature to all Firefox channels, protecting users from attacks launched via malicious websites. > Until today, Site Isolation could only be enabled by users of Firefox Nightly, the release channel used by Mozilla to test new features not yet ready for a wider rollout.