AssemblyVersion always included / verified with boxed List<T>

[lsallows]

Bug description
I am using the TypelessContractlessStandardResolver along with the options to omit the assembly version and allow assembly version mismatch. If the payload is just an object of type T then everything works as expected. If the payload is a List then the assembly version for type T is included and the deserialization fails if there is an assembly mismatch.

Repro steps

    [MessagePackObject]
    public class Message
    {
        [Key(0)]
        public string MessageName { get; set; }

        [Key(1)]
        public object Payload { get; set; }
    }

    [MessagePackObject]
    public class TestClass
    {
        [Key(0)]
        public int Prop1 { get; set; }
    }

    var msg = new Message()
    {
        MessageName = "MyMessage"
    };
               
    var testClass = new TestClass() { Prop1 = 1 };
    var payloadList = new List<TestClass>() { testClass };
    msg.Payload = payloadList;
    var opts = TypelessContractlessStandardResolver.Options
        .WithOmitAssemblyVersion(true)
        .WithAllowAssemblyVersionMismatch(true);
    
    // Includes Assembly Info - Not expected
    var bytes = MessagePack.MessagePackSerializer.Serialize(msg, opts);

    // Excludes Assembly info - Expected
    msg.Payload = testClass;
    bytes = MessagePack.MessagePackSerializer.Serialize(msg, opts);

Additional context

MessagePack 2.2.85
.NET Core 3.1

I am using MessagePack as the serializer for Service Fabric Remoting. Under this use case, the assembly versions will not always match between the client and the server.

[AArnott]

I can't even find that the library uses AllowAssemblyVersionMismatch anywhere. That would be a regression, so I'm taking a look.

[AArnott]

Oh, never mind. I found it:
https://github.com/neuecc/MessagePack-CSharp/blob/8e869d9c8cecbbf8f63e508cfb79d7339eca347d/src/MessagePack.UnityClient/Assets/Scripts/MessagePack/MessagePackSerializerOptions.cs#L132