ios – writing to Binding inside a Button motion triggers onDisappear

I’ve a struct:

struct Demo {
    struct Knowledge {
        var worth: Int
    }
    var information: [Data]
}

after which in some view I’ve:

struct SomeView: View {
    @Binding var demo: Demo
    var physique: some View {
        Button(motion: {
            demo.information[validIndex].worth = 5
        }) {
           Picture(systemName: "plus.circle")
                    .resizable()
                    .body(width: 50.0, peak: 50.0, alignment: .middle)
        }
    }
}

assume the var information: [Data] has greater than 5 components in it, and we’re simply making an attempt to replace an present worth once we press this button in SomeView. If I exploit SomeView like this:

struct DisappearView: View {
    @Binding var demo: Demo

    var physique: some View {
        ZStack {
           // different views/shapes, and so on
           SomeView(demo: $demo)
        }
        .onAppear {
          // do some stuff
        }
        .onDisappear {
         // do some stuff
        }
    }
}

the write line, demo.information[validIndex].worth = 5 upon button press triggers the .onDisappear within the mother or father View, and I can not work out why. I’ve used the debugger to step by means of and execute the code line by line, the array replace appears to work once I write it as an expression within the debugger, but when I resume the code it boots out of the view and triggers .onDisappear. If I remark out the write line, .onDisappear is not triggered once I press the button.