#1143 added type as a reserved field name because type is used in type annotations, which renames OpenAPI fields with the name type to type_.

This leads to extra confusion for users of the client because this common field name no longer matches the API spec.

The rationale given in #1143 (comment) was that this is due to local variable names, but Python supports shadowing (for built ins as well, such as type), to support this very reason. For example this code runs fine on Python 3.9+:

def f(a: type[int | str]) -> None:
    type = 1
    print(f"{type}: {a}")

f(int)

Output: 1: <class 'int'>

At a higher level, the Python core team makes a big effort to avoid these kinds of breaking changes that affect variable naming. For example, when pattern matching was added, match was added a soft keyword so that anyone using match as a local variable name would not be affected.