What can possible use of making a class friend and inheriting it also?

I was going through one of my local libraries and noticed the follwowing:

class Derived : public Base
{
        friend class Base; // serves as a factory
    protected:
        pthread_spinlock_t allocLock;
        bool isSafe{ true };

        Derived();
        char *funcA() override;

    public:
        void funcB( bool _in ) override;
        virtual ~Derived();
};

I am not able to understand if Base has been inherited then why it has been made a friend of Derived. Also how the comment serves as a factory make sense here?

If it were to access Base function, :: operator would have been sufficient.

Is it more related to Design approach?