TYPO3 Core

While persisting an object and the DataMapper is asked for the plainValue
of a property. The TypeHandlingUtility is using "is_subclass_of()" to check
if the given input is an instance of \TYPO3\CMS\Core\Type\TypeInterface.
Unfortunately, when passing a string into "is_subclass_of" it tries to
instantiate an object of that name. This will trigger the class auto loader.
Even worst, when the string contains an special char (like an umlaut) the
class cache will throw an exception (#1233057752). Thus persisting an object
with special chars in a property value is not possible at the moment.

This issue was already fixed in #54275 and reintroduced during a cleanup in #57255.