It looks as though GObject.Value is an introspected type with gi.Boxed and gobject.GBoxed as bases. The destruction of GValue's created in python and set to hold a boxed or object type will leak that reference after the GValue is collected.

An override could be added implementing __del__ which makes a call to "unset" to fix the leak. However, this might not be desired in the case of a pointer to a GValue passed as a parameter to a python vfunc with the transfer != GI_TRANSFER_EVERYTHING. Or rather we could expose the "free_on_dealloc" static property of gobject.GBoxed and check that within the __del__. For example:

class Value(GObjectModule.Value):
    def __del__(self):
        if self._free_on_dealloc:
            self.unset()

Value = override(Value)