この前たまたま見かけたのですが、この辺り関係していますか？

/// If the field has a property wrapper for which we will need to call the /// wrapper type's init(wrappedValue:, ...), call the function that performs /// that initialization and return the result. Otherwise, return \c arg.

https://github.com/swiftlang/swift/blob/main/lib/SILGen/SILGenConstructor.cpp#L249