MessagePack 3.1.4, targeting .NET 8.

I'm seeing a deadlock for a quite simple client/server solution. Basically it goes like this:

1. Client writes message X (112 bytes): SerializeAsync
2. Client reads (waits) for message Y (response to X): DeserializeAsync
3. Server reads message X (112 bytes): DeserializeAsync - blocks in second call in while loop. See below!

So the server never exits the read call, not allowing it to write an answer to the client. While debugging, I identified the cause of this. See this line in MessagePackSerializer.DeserializeAsync:

There, the server has read 112 bytes but the loop takes it back to the stream.ReadAsync() call where it blocks.

Bug or not?
Is this expected behavior? I asked it to deserialize a message, and it got all bytes needed for it. What am I missing here?

The message sent (112 bytes written and 112 bytes read)

[MessagePackObject]
[Union(0, typeof(HelloMessage))]
// Additional unions...
public abstract class PipeMessage
{
    [Key(0)]
    public required Guid Id { get; init; }
}

[MessagePackObject]
public sealed class HelloMessage : PipeMessage
{
    [Key(1)]
    public required Guid SessionId { get; init; }
    
    [Key(2)]
    public required string Secret { get; init; }

    [Key(3)]
    public required int ProtocolVersion { get; init; }
}