• Make typing_extensions.TypeAliasType's __module__ attribute writable. Backport of CPython PR #149172.
• Fix setting of __required_keys__ and __optional_keys__ when inheriting keys with the same name.
• Add support for AsyncIterator, io.Reader, io.Writer and os.PathLike protocols as bases for other protocls.
• Fix incorrect behaviour on Python 3.9 and Python 3.10 that meant that calling isinstance with typing_extensions.Concatenate[...] or typing_extensions.Unpack[...] as the first argument could have a different result in some situations depending on whether or not a profiling function had been set using sys.setprofile. This affected both CPython and PyPy implementations. Patch by Brian Schubert.
• Fix __init_subclass__() behavior in the presence of multiple inheritance involving an @deprecated-decorated base class. Backport of CPython PR #138210 by Brian Schubert.
• Raise TypeError when attempting to subclass typing_extensions.ParamSpec on Python 3.9. The typing implementation has always raised an error, and the typing_extensions implementation has raised an error on Python 3.10+ since typing_extensions v4.6.0. Patch by Brian Schubert.
• Add bound and variance parameters to TypeVarTuple.