TYPO3 Core

Patch set 2 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at http://review.typo3.org/42058

Patch set 3 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at http://review.typo3.org/42058

Hmm. It seems that:

admPanel.enable = 0
admPanel.enable.all = 0

In user pageTSconfig does the trick. I'm not sure if admPanel.enable = 0 is needed (it isn't respected, judging from the code) but in any case, it looks like the default value of the admPanel.enable.all has been altered from 0 to 1.

The method that makes this decision appears to be slightly illogical:

// typo3/sysext/backend/Classes/FrontendBackendUserAuthentication.php:89
                $this->extAdminConfig = $this->getTSConfigProp('admPanel');
                if (isset($this->extAdminConfig['enable.'])) {
                        foreach ($this->extAdminConfig['enable.'] as $value) {
                                if ($value) {
                                        $this->adminPanel = GeneralUtility::makeInstance(\TYPO3\CMS\Frontend\View\AdminPanelView::class);
                                        $this->extAdmEnabled = TRUE;
                                        break;
                                }
                        }
                }

In other words, anything at all enabled means the entire admin panel gets forcibly enabled with no way to disable i in bulk. Any option that can be enabled must be disabled or the panel and asset still shows.

Adding a check here if admPanel.enable is explicitly zero and avoiding entering the loop would fix the issue reported by OP.

Patch set 2 for branch master of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/44726