bpo-46655: allow stringized TypeAlias with get_type_hints by GBeauregard · Pull Request #31156 · python/cpython
This is a bit weird; it isn't a type, after all. However, _type_check is called as part of stringized annotation resolution so all valid typeforms need a code path to get through it or we will cause errors for get_type_hints calls that may not even be intended to inspect the typeform of issue (e.g. called on a module or class). It also needs to be able to pass through _type_check if you want the typeform to be able to be contained in an Annotated (probably not a concern for TypeAlias).
The most reasonable way I currently know to reach this is if you called get_type_hints on a module with a globally defined TypeAlias (that was stringized). See bpo for additional commentary.