Run the following program with OpenGL & Metal rendering pipelines separately.
1) -Dsun.java2d.metal=false -Dsun.java2d.uiScale=2.0
2) -Dsun.java2d.metal=true -Dsun.java2d.uiScale=2.0

It can be observed that the height of the frame/window is 44pixel lesser for (2) as compared to the height of the frame/window for (1)

Refer attached screenshots.

// Test Code start -----------------------------
import javax.swing.*;
import java.awt.*;
import java.awt.geom.Line2D;
import java.awt.geom.Rectangle2D;

class CustomPanel extends JPanel {
    @Override
    public void paint(Graphics g) {
        Graphics2D g2 = (Graphics2D) g;

        g2.setColor(Color.green);
        g2.fill(new Rectangle2D.Double(60, 60, 200, 200));

        g2.setStroke(new BasicStroke(5));
        g2.setColor(Color.BLUE);
        g2.draw(new Line2D.Double(180, 100, 300, 300));

        g2.setStroke(new BasicStroke(1));
        g2.setColor(Color.RED);
        g2.draw(new Line2D.Double(0, 0, 50, 50));
        g2.draw(new Rectangle2D.Double(100, 100, 150, 50));
    }


    @Override
    public Dimension getPreferredSize() {
        return new Dimension(300, 300);
    }
}

public class Metal_JFrame {

    public static void main(String[] args) {

        JFrame myFrame = new JFrame("Metal Frame");
        myFrame.setSize(300, 300);
        myFrame.add(new CustomPanel());

        myFrame.pack();
        myFrame.setVisible(true);
    }
}
// Test Code end ----------------------