Does the canvas view on top of the PDFView not re-render?

I added a canvas view using PDFPageOverlayViewProvider. When I zoom the PDFView, the drawing is scaled, but its quality becomes blurry. How can I fix this?

import SwiftUI
import PDFKit
import PencilKit
import CoreGraphics
 
struct ContentView: View {
    var body: some View {
        if
            let url = Bundle.main.url(forResource: "sample", withExtension: "pdf"),
            let data = try? Data(contentsOf: url),
            let document = PDFDocument(data: data)
        {
            PDFRepresentableView(document: document)
        } else {
            Text("fail")
        }
    }
}
 
#Preview {
    ContentView()
}
 
struct PDFRepresentableView: UIViewRepresentable {
    let document: PDFDocument
    let pdfView = PDFView()
    
    func makeUIView(context: Context) -> PDFView {
        pdfView.displayMode = .singlePageContinuous
        pdfView.usePageViewController(false)
        pdfView.displayDirection = .vertical
        
        pdfView.pageOverlayViewProvider = context.coordinator
        pdfView.document = document
        pdfView.autoScales = false
        pdfView.minScaleFactor = 0.7
        pdfView.maxScaleFactor = 4
        
        return pdfView
    }
 
    func updateUIView(_ uiView: PDFView, context: Context) {
        // Optional: update logic if needed
    }
 
    func makeCoordinator() -> CustomCoordinator {
        return CustomCoordinator(parent: self)
    }
}
 
class CustomCoordinator: NSObject, PDFPageOverlayViewProvider, PKCanvasViewDelegate {
    let parent: PDFRepresentableView
    
    init(parent: PDFRepresentableView) {
        self.parent = parent
    }
    
    func pdfView(_ view: PDFView, overlayViewFor page: PDFPage) -> UIView? {
        let result = UIView()
        let canvasView = PKCanvasView()
        canvasView.drawingPolicy = .anyInput
        
        canvasView.tool = PKInkingTool(.pen, color: .blue, width: 20)
        canvasView.translatesAutoresizingMaskIntoConstraints = false
        
        result.addSubview(canvasView)
        NSLayoutConstraint.activate([
            canvasView.leadingAnchor.constraint(equalTo: result.leadingAnchor),
            canvasView.trailingAnchor.constraint(equalTo: result.trailingAnchor),
            canvasView.topAnchor.constraint(equalTo: result.topAnchor),
            canvasView.bottomAnchor.constraint(equalTo: result.bottomAnchor)
        ])
        
        
        for subView in view.documentView?.subviews ?? [] {
            subView.isUserInteractionEnabled = true
        }
        
        result.layoutIfNeeded()
        return result
    }
}