If @deprecated is applied to a class which defines __new__ but not __init__, it applies this check from object.__new__(), causing a TypeError from code that otherwise works fine:

from typing_extensions import deprecated
  
@deprecated("something")
class OnlyHasNew:
     def __new__(cls, a: int, b: float) -> 'OnlyHasNew':
        obj = object.__new__(cls)
        obj.a = a
        obj.b = b
        return obj

OnlyHasNew(1, 2)  # TypeError: OnlyHasNew() takes no arguments

It seems like that check should be moved into the else: branch there. I originally found this when trying to deprecate a NamedTuple class, which is potentially a more likely way to run into this issue.