using System;

using System.Globalization;

​

var dto = DateTimeOffset.ParseExact("2019-07-16T15:07:35.4228725+02:00",

                                    new string[] { "yyyy-MM-dd'T'HH:mm:ss.FFFFFFFK" },

                                    CultureInfo.InvariantCulture,

                                    DateTimeStyles.None);

var ObservedAt = new DateTimeDst(dto);

Console.WriteLine(ObservedAt.DateTime.ToString("yyyy-MM-dd'T'HH:mm:ss.FFFFFFFK"));

Console.WriteLine(ObservedAt.Dst);

​

public struct DateTimeDst

{

    public DateTime DateTime;

    public bool Dst;

    public DateTimeDst(DateTime dt) {

        DateTime = dt;

        Dst = false;

    }

    public DateTimeDst(DateTimeOffset dto) {

        DateTime = dto.DateTime;

        Dst = dto.Offset.Hours != 1;

    }

}