这似乎是特定于在模拟器中的实际设备上运行的，我无法重现该问题。
“不支持的像素格式”的原因原来是渲染图像中的24位颜色深度，也可能是alpha层的存在。jpeg编码器需要8位色深，没有透明度（尽管我希望UIImage实现自动转换色深）。
以下代码将颜色深度转换为8位：

extension View {
    @MainActor func uiImageSnapshot() -> UIImage? {
        let renderer = ImageRenderer(content: self)

        // jpeg encoder requires that the image not have an alpha layer
        renderer.isOpaque = true

        guard let image = renderer.uiImage else { return nil }

        // jpeg encoder requires an 8-bit color depth (including the encoder used in Mail, Messages, etc.)
        return image.convertedToColorDepth(8)
    }
}

extension UIImage {
    func convertedToColorDepth(_ colorDepth: Int) -> UIImage? {
        guard let cgImage else {
            return nil
        }

        let colorSpace = CGColorSpaceCreateDeviceRGB()
        let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.premultipliedFirst.rawValue)

        guard let context = CGContext(data: nil, width: cgImage.width, height: cgImage.height, bitsPerComponent: colorDepth, bytesPerRow: 0, space: colorSpace, bitmapInfo: bitmapInfo.rawValue) else {
            return nil
        }

        let rect = CGRect(x: 0, y: 0, width: cgImage.width, height: cgImage.height)
        context.draw(cgImage, in: rect)

        guard let newCGImage = context.makeImage() else {
            return nil
        }

        return UIImage(cgImage: newCGImage)
    }
}