ALM QC 12.21, REST api, how to properly sign-out session?

Question

I have signed in to the REST api and got to query data from it.
Problem is: I've signed in each time I got data from the server, which created a lot of sessions. When I try to close the sessions through the /rest/authentication/sign-out - I get 200 OK response just like in the documentation.
Then I access /rest/is-authenticated with all the cookies I got from /sign-in(LWSSO, QCSession, XCSRF) and my Base64 encoded credentials. Even thought I just signed-out - it still returns my username(as if I'm still signed-in).

Flooding the server with sessions is not an option.

Answer 1

The end-point is /qcbin/authentication-point/logout

If the response header Expires key contains value 01 Jan 1970 `. It means your session is successfully terminated