CodeIgniter v4.3.8 and v4.4.0 Released!

Now preferApp works only when you request a classname without a namespace.

...

For example, in a controller (namespace App\Controllers), if you called config(Config\App::class) by mistake (note the class is missing the leading \), meaning you actually passed App\Controllers\Config\App. But that class does not exist, so now Factories will return null.

See https://codeigniter4.github.io/CodeIgnit...#factories

Your case is the same thing. 
Previously, classes were searched by short classname alone, but starting with 4.4.0, classes with namespaces are now searched only for that specified class.

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