FB20843042 is the feedback we filed which includes a sample project. What is the intent of foo(key: MyCustomTraitKey.self)? It was added in an effort to identify the source of the crash by minimizing types and functions used from system SDKs. The issue occurs with any function with the same signature. The original ossie wsa found when calling https://developer.apple.com/documentation/swiftui/environmentvalues/subscript(_:)-9zku