There are two reasons why it says you have Windows 10. Your UserAgent is Mozilla/5.0 (Windows '''NT 10.0'''; Win64; x64; rv:130.0) Gecko/20100101 Firefox/130.0 The NT kernel version on Windows 11 is the same as Windows 10 because it is based on the same kernel, hence the NT 10.0 in the Firefox UserAgent. https://en.wikipedia.org/wiki/Windows_NT The second is the Firefox useragent is basically set to show NT 10.0 anyways (which you will see with Firefox on Windows since Fx 116.0+) just as for macOS users it shows macOS 10.15 in UA even if they are using a more current macOS. See also <blockquote>See: *[https://bugzilla.mozilla.org/show_bug.cgi?id=1841425 1841425] - Hard code UA string's Windows version as 10.0 (<i>please do not comment in bug reports<br>https://bugzilla.mozilla.org/page.cgi?id=etiquette.html</i>) </blockquote>