Recently I noticed that the new PEP 604 Union type doesn't collect type variables:

from typing import TypeVar
T = TypeVar('T')

(int | list[T]).__parameters__

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'types.Union' object has no attribute '__parameters__'

Whereas the typing.Union version has __parameters__. Is this behavior intentional?

The downside to this is that things like this don't work:

alias: TypeAlias = int | list[T]
alias[str] # Error!