SAML Logout does not end the session completely 🤫

The pain for us is, that our user logout from our access page with SAML login and be redirected to the {mydomain} with the Status message “You successfully logged out” and then leave the internetcafe PC with this logout page. They think, all is done. But if a new User is on the PC, he just can click the SAML button that is still showing and are successfully re logged in. Or he can press the back Button on the browser and will be relogged in. Only a closing of the Browser is killing the SAML Ticket / session. Not nice I think =)
A logout should kill the SAML tiket or session in my opinion.

Is this a bug or do we missconfigure something?

Thanks in advance