Steps to reproduce:
- Log in and open frontend in 2 tabs;
- Log out in both tabs;
- Log in in first of both tabs. Observe that you are logged in;
- Press F5 in second tab and confirm form resubmission.
Logout data are resubmitted and you are logged out in both tabs.
There should be redirect after logout to clean post data like it was in 3.4 and earlier versions.