Depends on what container you put the ScrollPane in. Flip the boolean in the code below to see different issues.

package scrollpanetrails;

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.Menu;
import javafx.scene.control.MenuBar;
import javafx.scene.control.ScrollPane;
import javafx.scene.control.Tab;
import javafx.scene.control.TabPane;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class ScrollPaneTrails extends Application {
    
    @Override
    public void start(Stage primaryStage) {
        VBox vbox = new VBox(4);
        vbox.setStyle("-fx-background-color: green");
        ScrollPane sp = new ScrollPane(vbox);
        sp.setStyle("-fx-background-color: purple;");
        for(int i = 0; i < 20; i++) {
            vbox.getChildren().add(new Label("Scroll slowly and look carefully at the quality of the revealed text "+i));
        }

        BorderPane root = new BorderPane();
MenuBar menus = new MenuBar();
root.setTop(menus);
menus.getMenus().add(new Menu("File"));

// CHANGE THIS TO FALSE to see a different problem
// Expand the window horizontally so that the green vbox has some extra
// space to the right.. now there is nan extra bit of ScrollPane
// background showing at the bottom of the viewport. It is copied into
// the viewport when you scroll
        if (true) {
            Tab tab = new Tab("My Tab");
            tab.setContent(sp);
            TabPane tabs = new TabPane();
            tabs.getStyleClass().add(TabPane.STYLE_CLASS_FLOATING);
            tabs.setTabClosingPolicy(TabPane.TabClosingPolicy.UNAVAILABLE);
            tabs.getTabs().add(tab);
            root.setCenter(tabs);
        } else {
            root.setCenter(sp);
        }
        Scene scene = new Scene(root, 300, 250);
        primaryStage.setTitle("Scrolling Artifacts!");
        primaryStage.setScene(scene);
        primaryStage.show();

    }

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