TextEditor seems to have a default white background. So the following is not working and it displayed as white instead of defined red:
TextEditor is backed by UITextView. So you need to get rid of the UITextView's backgroundColor first and then you can set any View to the background.
struct ContentView: View {
init() {
UITextView.appearance().backgroundColor = .clear
}
var body: some View {
TextEditor(text: .constant("Placeholder"))
.background(Color.red)
}
}