https://bugzilla.mozilla.org/show_bug.cgi?id=1679929 caps the macOS version exposed in the User-Agent string to 10.15.
The motivation that set this in motion is the Web compat impact of sites not expecting to see a version starting with 11. The reason for not exposing Big Sur as 10.16 is that Safari capped the version and capping the version has a privacy benefit going forward while the utility of exposing the macOS version is questionable especially after Safari capped it. https://bugs.webkit.org/show_bug.cgi?id=217364 As for why not do even better for privacy and report 10.15 on older versions of macOS, capping the version is a more prudent change. Chrome will also cap the version like Safari in its UA string, but Chrome will expose the real version via Sec-CH-UA-Platform-Version, which neither Safari nor Firefox supports. (Client Hints in general and the Sec-CH-UA-* parts in particular are beyond the scope of this email.) https://groups.google.com/a/chromium.org/g/blink-dev/c/hAI4QoX6rEo/m/qQNPThr0AAAJ So far, the use case why Web developers would prefer to distinguish Safari on Catalina vs. Safari on Big Sur relates to WebP support, but the issue is moot for both Firefox and Chrome, as Firefox and Chrome advertise WebP via the Accept header and don't rely on the OS decoder. -- Henri Sivonen hsivo...@mozilla.com _______________________________________________ dev-platform mailing list firstname.lastname@example.org https://lists.mozilla.org/listinfo/dev-platform