__doc__ returns None from Qt subclass

from PyQt6.QtCore import QObject as PyQt6QObject
from PySide6.QtCore import QObject as PySide6QObject


class Foo:
    """Foo docs"""


class PyQt6Foo(PyQt6QObject):
    """PyQt6Foo docs"""


class PySide6Foo(PySide6QObject):
    """PySide6Foo docs"""


print("* From class:")
print("Foo:", Foo.__doc__)
print("PyQt6QObject:", PyQt6QObject.__doc__)
print("PySide6QObject:", PySide6QObject.__doc__)
print("PyQt6Foo:", PyQt6Foo.__doc__)
print("PySide6Foo:", PySide6Foo.__doc__)
print("* From instance:")
print("Foo:", Foo().__doc__)
print("PyQt6Foo:", PyQt6Foo().__doc__)
print("PySide6Foo:", PySide6Foo().__doc__)

* From class:
Foo: Foo docs
PyQt6QObject: QObject(parent: QObject = None)
PySide6QObject: QObject(self, parent: Optional[PySide6.QtCore.QObject] = None) -> None
PyQt6Foo: PyQt6Foo docs
PySide6Foo: None
* From instance:
Foo: Foo docs
PyQt6Foo: PyQt6Foo docs
PySide6Foo: PySide6Foo docs