The MultiWriteBagOStuff class was changed at some point to not call static ObjectCache::newFromParams from its constructor, as this bypassed dependency injection principles.
However, we never compensated for this by injecting things like $logger from a higher level into the configuration entries in $wgObjectCaches that use MultiWriteBagOStuff.
MultiWriteBag is used at WMF for its ParserCache as mysql-multiwrite: 0=MemcachedBag, 1=SqlBag. The outer MultiWrite bag naturally gets dependencies injected when it is obtained via ObjectCache::getInstance from service wiring. However, the inner bags have lost the state that would normally be injected.
From wmf-config/CommonSettings.php:
$wgObjectCaches['mysql-multiwrite'] = [ 'class' => 'MultiWriteBagOStuff', 'caches' => [ 0 => [ 'factory' => [ 'ObjectCache', 'getInstance' ], 'args' => [ 'mcrouter-with-onhost-tier' ] ], 1 => [ 'class' => 'SqlBagOStuff', 'servers' => $pcServers, 'purgePeriod' => 0, 'tableName' => 'pc', 'shards' => 256, ], ], ];
The result is, for example, when using "Verbose logs" via WikimediaDebug and performing an edit or purge, that there are no log entries about the writes to the ParserCache database.