I was also unable to replicate on any of 3.7-3.11, including 3.9.6. Is it possible that one of your Python stdlib source files was modified? Does this still happen with a fresh install of Python?

Does your problem still happen if you run the file using a python executable directly rather than using IPython/Jupyter? If it's just a problem with Jupyter, this bug report belongs there.

Can you run:

>>> from concurrent.futures import ThreadPoolExecutor as TPE
>>> TPE.__mro__
(<class 'concurrent.futures.thread.ThreadPoolExecutor'>, <class 'concurrent.futures._base.Executor'>, <class 'object'>)
>>> TPE.__mro__[1]
<class 'concurrent.futures._base.Executor'>
>>> dir(TPE.__mro__[1])
['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__enter__', '__eq__', '__exit__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'map', 'shutdown', 'submit']