How do I maintain transparency when loading WebP format images on iOS?

Question

I have a function to import images from an array of NSItemProvider (passed from a PHPickerViewController) and I need to maintain transparency in the images. Any images in PNG format are correctly maintaining transparency but WebP images are not. The image import code is as follows:

private func save(itemProviders: [NSItemProvider]) async throws -> Int {
    return try await withCheckedThrowingContinuation({ continuation in
        let group = DispatchGroup()
        var failureCount = 0
        for item in itemProviders {
            // webp format image
            if item.hasItemConformingToTypeIdentifier(UTType.webP.identifier) {
                group.enter()
                item.loadDataRepresentation(forTypeIdentifier: UTType.webP.identifier) { data, error in
                    defer {
                        group.leave()
                    }
                    guard let data, let image = UIImage(data: data) else {
                        return
                    }
                    self.saveImage(image)
                }
            }
            else if item.canLoadObject(ofClass: UIImage.self) {
                // other image formats, including PNG
                group.enter()
                item.loadObject(ofClass: UIImage.self) { (image, error) in
                    defer {
                        group.leave()
                    }
                    guard let image = image as? UIImage else {
                        return
                    }

                    self.saveImage(image)
                }
            }
            else {
                failureCount += 1
            }
        }
        group.notify(queue: .main) {
            continuation.resume(returning: failureCount)
        }
    })
}

Please note that the saveImage function is a simple resize and save to disk function, and I have been able to verify that transparency is not being lost during that step.

It seems as though transparency is being lost during the call to item.loadDataRepresentation(forTypeIdentifier: UTType.webP.identifier) or when the resulting Data is used to instantiate a UIImage. The code in the WebP handling block seems to be irreducibly simple though so I'm not sure how I can possibly fix this issue.