Is it Leap 15.6 is in use?

English Install/Boot/Login
1

https://en.opensuse.org/Lifetime
Leap 15.6 haven’t been added to the discontinued version of openSUSE, when you plan to stop the support of security updates?

2

That Wiki page is out-of-date, see also:

https://en.opensuse.org/openSUSE:Roadmap