NSUrlSessionTaskDelegate DidSendBodyData totalBytesSent inaccurate

Question

NSUrlSessionTaskDelegate DidSendBodyData totalBytesSent seems to indicate that upload progress is being reported out of order.
I created a simple test with a single upload, and logged the value of totalBytesSent every time it was called.

For example,
totalBytesSent 3571712
totalBytesSent 3637248
totalBytesSent 3604480
totalBytesSent 3670016

I am seeing this happen around 1-3 times for a 5 MB file. I was wondering if anyone else could confirm this is a known issue, and I cannot rely on these being in the correct order.

Delegate:

    // For use with NSUrlSession that is configured for HttpMaximumConnectionsPerHost = 1
    public class TestUploadDelegate : NSUrlSessionTaskDelegate
    {
        public override void DidSendBodyData(NSUrlSession session, NSUrlSessionTask task, long bytesSent, long totalBytesSent, long totalBytesExpectedToSend)
        {
             Console.WriteLine($"totalBytesSent {totalBytesSent}");
        }
    }

NSUrlSession creation:

    public NSUrlSession GetFileHostUrlSession()
    {
        if (this.fileHostUrlSession == null)
        {
            using var configuration = NSUrlSessionConfiguration.CreateBackgroundSessionConfiguration(FileHostSessionIdentifier);
            configuration.AllowsCellularAccess = true;
            configuration.WaitsForConnectivity = true;
            configuration.ShouldUseExtendedBackgroundIdleMode = true;
            configuration.SessionSendsLaunchEvents = true;
            configuration.Discretionary = false;
            configuration.HttpMaximumConnectionsPerHost = 1; // Set to 1 for testing
            this.fileHostUrlSession = NSUrlSession.FromConfiguration(configuration, new TestUploadDelegate() as INSUrlSessionDelegate, new NSOperationQueue());
        }
        return this.fileHostUrlSession;
    }