TextField is mutating its model when not editing?

This minimal code demonstrates a problem I'm having. As you adjust the Slider (high precision numbers), the TextField sets the model, changing the number's precision to its format.

But I only want it to use the 3-digit fraction for display, or if the user edits in the field. It shouldn't be mutating the model just because it's displaying the value, no?

Is it a bug? It doesn't seem right to me.

struct ContentView: View {
    @State var number: Double = 0

    // wrap binding to log the `set` calls
    var textFieldBinding: Binding<Double> {
        Binding { number } set: {
            print("Setting from TextField: \($0)")
            number = $0
        }
    }

    var sliderBinding: Binding<Double> {
        Binding { number } set: {
            print("Setting from Slider: \($0)")
            number = $0
        }
    }

    var body: some View {
        VStack {
            TextField("Number", value: textFieldBinding, format: .number.precision(.fractionLength(3)))
            Slider(value: sliderBinding, in: 0...5.0)
        }.frame(maxWidth: 300)
    }
}

When you drag the slider, you see stuff like:

Setting from Slider: 1.0073260217905045
Setting from TextField: 1.007
...