Why does the WordPress official website show a fake release date?

It’s not incorrect, let alone ‘fake’. Security updates are often released as minor versions of previous releases.

See the release notes on the page you linked to:

From the WordPress 4.9.2 release post: WordPress versions 4.9 and
are affected by an XSS vulnerability in the Flash fallback
files in MediaElement 4.x, a library that is included with WordPress

That issue also affected 4.4. Since WordPress automatically updates to minor versions, this version of 4.4 was released at the same time to ensure sites received the fix even if they were holding off updating to the next major versions.