SwiftUI TextField keyboard flashes and breaks typing in other languages

https://youtu.be/ngExUJ7gyb8

Please observe the different behavior between system keyboard and the one using SwiftUI.

The first 5 seconds using spotlight search, you'll notice the typing is complete and the word picker does not flash for every character input.

In the last 5 second, you'll notice using SwiftUI's keyboard, the typing will be break every couple characters, and the word picker flashes for every new character input.

The same behavior can be observed using the simplest code

struct ContentView: View {
@State private var inputText = ""

var body: some View {
    VStack(spacing: 10.0) {
        TextField("Tap here", text: $inputText)
    }
}

}

Is that a bug of SwiftUI? Or did I miss something?