Images are overwritten when modifying a PDF iOS

I have an application that allows a user to draw on a PDF. The user's drawing is saved as an image which is then added to an existing PDF. The issue I encounter is when a user has already drawn 2 images. For some reason, saving the 3rd image cause the 2nd image to be overwritten by the first. Below is an example.

PDF example:

The PDF above should read First, Second, Third; however, the 2nd image was overwritten by the first.

Below is my code for embedding an image into the PDF. Note I also tried this with PDFKit and have experienced the same result:

func saveImageToPDF(path: String , drawnImage: UIImage, x: CGFloat, y: CGFloat, width: CGFloat, height: CGFloat, pageIndex: Int) {
    if  let pdf = CGPDFDocument(NSURL(fileURLWithPath: path)) {
        let pageCount = pdf.numberOfPages
        
        // Write to file
        UIGraphicsBeginPDFContextToFile(path, CGRect.zero, nil)
        for index in 1...pageCount {
            let page =  pdf.page(at: index)
            let pageFrame = page?.getBoxRect(.mediaBox)
            
            if (pageFrame != nil) {
                UIGraphicsBeginPDFPageWithInfo(pageFrame!, nil)
                
                let pdfContext = UIGraphicsGetCurrentContext()
                
                // Draw existing page
                pdfContext?.saveGState()
                
                pdfContext?.scaleBy(x: 1, y: -1)
                pdfContext?.translateBy(x: 0, y: -pageFrame!.size.height)
                pdfContext?.drawPDFPage(page!)
                pdfContext?.restoreGState()
                
                // Draw image on top of page
                if (index == (pageIndex + 1)) {
                    drawnImage.draw(in: CGRect(x: x, y: y, width: width, height: height))
                }
            }
        }
        UIGraphicsEndPDFContext()
    }
}

Note: I only seem to encounter this issue on iOS 15. Running the same code on iOS 14 works like a charm.

Should I consider this a bug on iOS 15, or is there something I'm missing?

Thanks in advance!

After reaching out to Apple's technical support. They concluded it was an issue with iOS 15.

Here is a sample project that replicates the issue exactly: https://github.com/Manguelo/test-pdf-issue

Note the application should be run on iOS 15.0

According to the PDFKit team this bug should be addressed in iOS 15.2 beta 3.