Bad display for JavaFX WebView under macOS

We are using JavaFX WebView as our in-app browser. It works well under Windows 10.

However, when we run in under macOS Catalina 10.15.7, all display gone hair wire. The app is run on Java 8.

Here's the code for our simple in-app browser.

SimpleSwingBrowser.java

public class SimpleSwingBrowser extends JDialog {
 
    private final JFXPanel jfxPanel = new JFXPanel();
    private WebEngine engine;
    private String loadedURL = null;
    private final JPanel panel = new JPanel(new BorderLayout());
 
    public SimpleSwingBrowser() {
        super(JStock.instance(), JDialog.ModalityType.APPLICATION_MODAL);
        initComponents();
    }

    
    private void initComponents() {
        createScene();
  
        // http://stackoverflow.com/questions/11269632/javafx-hmtleditor-doesnt-react-on-return-key
        jfxPanel.addKeyListener(new KeyAdapter() {
            @Override
            public void keyTyped(KeyEvent e) {
                if (e.getKeyChar() == 10) {
                    e.setKeyChar((char) 13);
                    Toolkit.getDefaultToolkit().getSystemEventQueue().postEvent(e);
                }
            }
        });

        panel.add(jfxPanel, BorderLayout.CENTER);
        
        getContentPane().add(panel);
        
        java.awt.Dimension screenSize = java.awt.Toolkit.getDefaultToolkit().getScreenSize();
        setBounds((screenSize.width-460)/2, (screenSize.height-680)/2, 460, 680);
    }
    
    private void createScene() {
 
        Platform.runLater(new Runnable() {
            @Override 
            public void run() {
                final WebView view = new WebView();
                engine = view.getEngine();
                
                engine.titleProperty().addListener(new ChangeListener<String>() {
                    @Override
                    public void changed(ObservableValue<? extends String> observable, String oldValue, final String newValue) {
                        SwingUtilities.invokeLater(new Runnable() {
                            @Override 
                            public void run() {
                                SimpleSwingBrowser.this.setTitle(newValue);
                            }
                        });
                    }
                });
 
                engine.getLoadWorker().stateProperty().addListener(new ChangeListener<State>() {

                    @Override
                    public void changed(ObservableValue<? extends State> observable, State oldValue, final State newValue) {
                        if (newValue == FAILED) {
                            final int result = JOptionPane.showConfirmDialog(
                                panel,
                                MessagesBundle.getString("error_message_unable_connect_to_internet"),
                                MessagesBundle.getString("error_title_unable_connect_to_internet"),
                                JOptionPane.YES_NO_OPTION);
                            
                            if (result == JOptionPane.YES_OPTION) {
                                if (loadedURL != null) {
                                    engine.load(loadedURL);
                                }
                            }
                        }
                    }
                });
                
                // http://stackoverflow.com/questions/11206942/how-to-hide-scrollbars-in-the-javafx-webview
                // hide webview scrollbars whenever they appear.
                view.getChildrenUnmodifiable().addListener(new ListChangeListener<Node>() {
                    @Override 
                    public void onChanged(Change<? extends Node> change) {
                        Set<Node> deadSeaScrolls = view.lookupAll(".scroll-bar");
                        for (Node scroll : deadSeaScrolls) {
                            scroll.setVisible(false);
                        }
                    }
                });
                
                jfxPanel.setScene(new Scene(view));
            }
        });
    }
 
    public void loadURL(final String url) {
        Platform.runLater(new Runnable() {
            @Override 
            public void run() {
                String tmp = toURL(url);
                
                if (tmp == null) {
                    tmp = toURL("http://" + url);
                }
 
                loadedURL = tmp;
                engine.load(tmp);
            }
        });
    }

    private static String toURL(String str) {
        try {
            return new URL(str).toExternalForm();
        } catch (MalformedURLException exception) {
            return null;
        }
    }
}

Any idea why this happens? Is there anything I can do to resolve? Thanks.