[demetris]

Do you know what user agent the browsers send?

I tried with Windows 7 (Firefox 115) and it reports Windows 7.

It seems though that it cannot distinguish between Windows 10 and Windows 11, so, without looking further, I suppose the detection is based on the User-Agent string? (The OS version browsers report on Windows is frozen, so Windows 10 and Windows 11 have the same version there.)