CS0173 in dotnet sdk 8.0.300pre3 and netstandard2.0

CS0173.netstd2.0.dynamic.cs

using System;

namespace a
{
    public class Class1
    {
        public static void X()
        {
            dynamic x = GetDynamic();
            // CS0173 with .NET SDK 8.0.300pre3 and netstandard2.0
            var moge = string.IsNullOrEmpty(x.A) ? null : DateTime.Parse(x.A);
            Console.WriteLine($"{x}");
        }
        static object GetDynamic()
        {
            return new { A = DateTime.Now.ToString("yyyy/MM/dd HH-mm-ss") };
        }
    }
}