RedHat 9 packages, versions and patchs

[Martin HAMANT]

Hi, 

I would like to understand from which upstream branch RedHat's patchs are coming and why. For instance on RHEL9 we currently have varnish-6.6.2-6.el9_6.1.
I suppose RedHat is applying (backporting) security patchs on top of this _old_ release, but from which upstream branch does it comes ? Is this from the 6.0.x LTS branch or newer ?

Last question; do you know what is the reason behind this specific '6.6.2' version in RedHat 9 ? (rather than a LTS one for instance)

Thank you for your insight,

Regards,

Martin