I’m a JavaFX beginner and I’m not sure how JavaFX handles input method positioning.
This issue can be reproduced on both Windows 11 and Windows 10, as well as with JavaFX 17 and JavaFX 22.

Sample code

public class InputTest extends Application {

    public static void main(String[] args) {
        launch(args);
    }

    @Override
    public void start(Stage stage) throws Exception {
        StackPane root = new StackPane();
        stage.setScene(new Scene(root, 300, 300));
        stage.show();
        Popup popup = new Popup();
        popup.getContent().add(new TextField());
        popup.show(stage);
    }

}