What is the Azure Bus Service Queue Listener replacement for .NET 5+?

Using the ServiceBusProcessor

string connectionString = "<connection_string>";
string queueName = "<queue_name>";

// since ServiceBusClient implements IAsyncDisposable we create it with "await using"
await using var client = new ServiceBusClient(connectionString);

var options = new ServiceBusProcessorOptions
{
    // By default or when AutoCompleteMessages is set to true, the processor will complete the message after executing the message handler
    // Set AutoCompleteMessages to false to [settle messages](https://learn.microsoft.com/en-us/azure/service-bus-messaging/message-transfers-locks-settlement#peeklock) on your own.
    // In both cases, if the message handler throws an exception without settling the message, the processor will abandon the message.
    AutoCompleteMessages = false,

    // I can also allow for multi-threading
    MaxConcurrentCalls = 2
};

// create a processor that we can use to process the messages
await using ServiceBusProcessor processor = client.CreateProcessor(queueName, options);

// configure the message and error handler to use
processor.ProcessMessageAsync += MessageHandler;
processor.ProcessErrorAsync += ErrorHandler;

async Task MessageHandler(ProcessMessageEventArgs args)
{
    string body = args.Message.Body.ToString();
    Console.WriteLine(body);

    // we can evaluate application logic and use that to determine how to settle the message.
    await args.CompleteMessageAsync(args.Message);
}

Task ErrorHandler(ProcessErrorEventArgs args)
{
    // the error source tells me at what point in the processing an error occurred
    Console.WriteLine(args.ErrorSource);
    // the fully qualified namespace is available
    Console.WriteLine(args.FullyQualifiedNamespace);
    // as well as the entity path
    Console.WriteLine(args.EntityPath);
    Console.WriteLine(args.Exception.ToString());
    return Task.CompletedTask;
}

// start processing
await processor.StartProcessingAsync();