RequestMiddlewares.php: new handling? (TYPO3 Extbase) - typo3

Question

This used to work in TYPO3 9 and TYPO3 10 but is not working from me in TYPO3 11:
EXTDIR/Configuration/RequestMiddlewares.php
<?php
return [
'frontend' => [
'varioous/rest/mail-chimp-middleware' => [
'target' => Varioous\Rest\MailChimpMiddleware::class,
'before' => [
'typo3/cms-frontend/eid',
'typo3/cms-frontend/tsfe',
],
],
],
];
I've looked at this description here https://docs.typo3.org/m/typo3/reference-coreapi/11.5/en-us/ApiOverview/RequestHandling/Index.html but I can't find the problem. The code is from this example: https://various.at/news/typo3-tipps-und-tricks-psr-15-mideelware-am-beispiel-mailchimp-webhook and has been adjusted to a custom made extension that has been working fine with TYPO3 9 and TYPO3 10. The particular extension belongs to the customer and I am not permitted to post it here. It is configured exactly as the mailchimp extension is in the how-to and I am sure the author used that how-to as a reference. As it seems, the mailchimp extension from the TER stopped using middleware - so I can't use the current version as a reference to fix my problem.
With this temporary workaround it's working fine:
<?php
return [
'frontend' => [
'varioous/rest/mail-chimp-middleware' => [
'target' => Varioous\Rest\MailChimpMiddleware::class,
'before' => [
# 'typo3/cms-frontend/eid',
# 'typo3/cms-frontend/tsfe',
],
],
],
];
How do I have to adjust the references to 'typo3/cms-frontend/eid' and 'typo3/cms-frontend/tsfe' for TYPO3 11? When I look up HTTP Middlewares (PSR-15) in the Configuration BackEnd module I can find them in the frontend category:
typo3/cms-frontend/eid = TYPO3\CMS\Frontend\Middleware\EidHandler
typo3/cms-frontend/tsfe = TYPO3\CMS\Frontend\Middleware\TypoScriptFrontendInitialization
FYI Further description of the Problem:
Once the extension is activated, ALL local extbase extensions stop working. For Example:
#1316104317 TYPO3\CMS\Extbase\Mvc\Exception
The default controller for extension "News" and plugin "Pi1" can not be determined. Please check for TYPO3\CMS\Extbase\Utility\ExtensionUtility::configurePlugin() in your ext_localconf.php.
Of course there is nothing wrong with the news extension. I temporarily added a debug output in the file typo3/sysext/extbase/Classes/Mvc/Web/RequestBuilder.php
protected function loadDefaultValues()
{
$configuration = $this->configurationManager->getConfiguration(ConfigurationManagerInterface::CONFIGURATION_TYPE_FRAMEWORK);
print_r($configuration);
When the extension with the middleware is activated, the value "controllerConfiguration" in the array returned from the ConfigurationManager is empty (for all local extensions).