With ScrollPane content composed of Labels (text only) within HBox-es within a VBox, all with borders, scrolling up& down (even slowly) introduces distortions (borders get "lost");
I do not recall seeing this issue in earlier Java 8 versions.
The following code exhibits the behavior on my system:

import javafx.application.Application;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.ScrollPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class TestSP extends Application {
;
private final String STYLE = ""
+"-fx-alignment: center;"
+"-fx-border-color: black;"
+"-fx-border-width: 2;"
+"-fx-border-radius: 8;"
+"-fx-padding: 3;"
+"-fx-text-wrap: true;"
;


VBox root = new VBox();
Scene scene = new Scene(root);
    
public static void main(String[] args) {
        launch(args);
    }
    @Override
    public void start(Stage primaryStage) {
          primaryStage.setWidth(800);
        primaryStage.setHeight(600);
        
        primaryStage.setScene(scene);
        primaryStage.show();
        root.getChildren().add(createPanel());
    }
   
    int ind=0;
      
    private Node createBlock() {
     HBox blk = new HBox(5);
     blk.setStyle(STYLE);
     for (int i=0;i<6;i++) {
     Label l= new Label("This is label #"+ind++);
         l.setStyle(STYLE);
     blk.getChildren().add(l);
     }
     return blk;
    }
    
    
    private ScrollPane createPanel() {
     ScrollPane sp = new ScrollPane();
        VBox.setVgrow(sp, Priority.ALWAYS);
     VBox vb = new VBox(10);
     sp.setContent(vb);
     for (int i=0;i<20;i++)
     vb.getChildren().add(createBlock());
     sp.setStyle(STYLE);
     return sp;
    }

}