C# Big Equality Comparer

BigComparer.cs

public class BigComparer<T> : IBigEqualityComparer<T>
    {
        private static FNV1a64 hash;
        private static Type _type;
        public bool Equals(T x, T y)
        {
            if (x == null || y == null)
                return false;
            return object.Equals((T)x, (T)y);
        }
        public long GetHashCode(T obj)
        {
            if (hash == null)
                hash = new FNV1a64();
            if (_type == null)
                _type = obj.GetType();
            return hash.ComputeHash(Converters.GetBytesObject(obj,_type)).ToLong();
        }

    }
    
   public interface IBigEqualityComparer<in T>
    {
        bool Equals(T x, T y);
        long GetHashCode(T obj);
    }