There are two related, but different strands of conversation here:

• collections.abc.ByteString is useless and confusing: Deprecate and schedule removal of collections.abc.ByteString and typing.ByteString #91896
• That bytes can be used as a shorthand for typing.ByteString and includes memoryview and bytearray https://peps.python.org/pep-0688/

However, there is an additional issue! collections.abc.ByteString is not an accurate replacement for typing.ByteString! collections.abc.ByteString only registers bytes and bytearray, whereas typing.ByteString is documented as also representing a memoryview. This is an issue regardless of the above two related conversations.

For this issue we could:

• Move the documentation of typing.ByteString out from under the "Corresponding to collections in collections.abc" section to the "Other concrete types" section
• Remove all mention of collections.abc.ByteString from typing.rst
• Keep the mention of typing.ByteString as being deprecated, but change the reason. ByteString is not a generic type and collections.abc.ByteString is not a semantic replacement for it as above, so the current reason is wrong on two counts
• Define typing.ByteString in typeshed as a simple Union, and not the Sequence[int] thing it is right now.
• Define typing.ByteString as a Union in typing.py instead of the generic alias it is now(?)

Here's how this relates to the other two strands of conversation:

• We should also remove the note about the bytes shorthand from the docs
• We should deprecate both typing.ByteString and collections.abc.ByteString. I'm fine with going slow on the removal of typing.ByteString, since once it's a union in typeshed it's not causing much harm. But ideally we can remove collections.abc.ByteString in 3.14, since its isinstance behaviour is not what you want.

cc @JelleZijlstra