What changed in Asp.Net Core 2.1 to introduce an abigous match for getting the contains method with reflection

In Asp.Net Core 2.0 the following method worked without any exceptions:

    private static Expression Contains(Expression member, ConstantExpression constant)
    {
        return Expression.Call(member, typeof(String).GetMethod("Contains"), constant);
    }

But as soon as we moved to 2.1 it threw an ambiguous match exception. We where able to correct the issue by providing a type argument. Shown in the message below:

        private static Expression Contains(Expression member, ConstantExpression constant)
        {
            return Expression.Call(member, typeof(String).GetMethod("Contains", new Type[] {typeof(string) }), constant);
        }

We haven't had any other issues like this since the switch, but I was curios if there was a change that will make this issue occur in other places.