TYPO3 Core

Patch set 1 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/83012

Can not reproduce, tested with:

ext_localconf.php

use TYPO3\CMS\Core\Cache\Frontend\VariableFrontend;
use TYPO3\CMS\Core\Cache\Backend\SimpleFileBackend;

$GLOBALS['TYPO3_CONF_VARS']['SYS']['caching']['cacheConfigurations']['mycache'] = [
    'frontend' => VariableFrontend::class,
    'backend' => SimpleFileBackend::class,
];

Follow commands reveal that flushing works:

mkdir typo3temp/var/cache/data/mycache
touch typo3temp/var/cache/data/mycache/foo
bin/typo3 cache:flush
LC_ALL=C ls typo3temp/var/cache/data/mycache/foo
ls: cannot access 'typo3temp/var/cache/data/mycache/foo': No such file or directory

Note that the cache-group all is assigned due to default-cache-configuration and will be returned by the CacheManager (if your cache is properly registered in ext_localconf.php). This group is then included in the CacheFlushEvent and will be flushed by the CacheManager flush-event-handler.

Patch set 2 for branch main of project Packages/TYPO3.CMS has been pushed to the review server.
It is available at https://review.typo3.org/c/Packages/TYPO3.CMS/+/83012

Closing here, there is no bug, as written in https://review.typo3.org/c/Packages/TYPO3.CMS/+/83012/2#message-0497d77da1ea845495cdf188ebcc4b70fa561e95