SwiftUI: @StateObject.init(wrappedValue:) gotcha

.swift

struct Parent: View {
	@State private var foo = "foo" {
		didSet { print("Parent", foo) }
	}

	var body: some View {
		VStack {
			Inner(value: foo)
      
			Button("Parent Double") {
				foo = [foo, foo].joined(separator: ":")
			}
		}
	}
}

class VM: ObservableObject {
	@Published var value: String = "" {
		didSet { print("Inner", value) }
	}

	init(value: String) {
		self.value = value
	}

	func double() {
		value = [value, value].joined(separator: " ")
	}
}

struct Inner: View {
	@StateObject private var vm: VM

	init(value: String) {
		self._vm = .init(wrappedValue: .init(value: value))
	}

	var body: some View {
		VStack {
			Text("Value: \(vm.value)")

			Button("Inner Double") { vm.double() }
		}
	}
}