mypy is unable to narrow a union type that includes a `StrEnum` subclass and a `Literal`

[exg]

Bug Report

As per the title, see the gist for an example. The issue does not occur when using Enum instead of StrEnum.

To Reproduce

https://mypy-play.net/?gist=cf9926c276e8fe0f48d7d20b7ebf2b6e

Expected Behavior

The output should be

main.py:12: note: Revealed type is "Literal['none']"
main.py:14: note: Revealed type is "__main__.Color"

Actual Behavior

The output is

main.py:12: note: Revealed type is "__main__.Color | Literal['none']"
main.py:14: note: Revealed type is "__main__.Color | Literal['none']"

Your Environment

• Mypy version used: 1.19.1