TYPO3 Core

The reason for this behavior is that

feUser->setCookie = SetCookieBehaviour::Remove is not applied anymore.

One of the reasons is that EXT:felogin is actually doing a redirect. This means, that LoginController propagates a Extbase Response and sets headers directly via header() - then, our middleware does not set the cookie properly anymore when logging out to remove the cookie (in FrontendUserAuthenticator.php and AbstractApplication.php).

My workaround was to adapt Extbase's Bootstrap.php around line 192ff like this:

if (headers_sent() === false) {
// added by benni 
            if ($response->getStatusCode() >= 300) {
                throw new PropagateResponseException($response);
            }
// added by benni 
            foreach ($response->getHeaders() as $name => $values) {
                foreach ($values as $value) {
                    header(sprintf('%s: %s', $name, $value));
                }
            }