Handling dates and times between C# API and Typescript

Question

I am having trouble correctly transporting my date and timezone to my backend. I am using a DateTimeOffset in the backend and a TypeScript date in the frontend. I attempted to convert the date to the correct format using moment.js, but unfortunately, I was unsuccessful. Can you please assist me with this issue? I am unsure whether to convert the backend DateTimeOffset to a string, as it is difficult to implement and not the optimal solution. Unfortunately, my research has not yielded any helpful results. I am using the datetime-local text field from Fluent UI, which requires me to convert the date format multiple times.

Frontend:

    //model
    export interface Setting {
            validFrom?: Date;
            validTo?: Date;
        }
    //apiService
    public async createSetting(setting: Setting): Promise<any> {
    let postUrl = ``
    try {
      return await axios.post(postUrl, setting)
    } catch (ex) {
      return ex
    }  
}


// Formating for saving
        const parseDateForSave = (dateString?: string) => {
            console.log("parseDateForSave: " +dateString);
            return dateString ? moment.tz(dateString, "Europe/Berlin").toDate() : undefined;
        };


//format for displaying in textfield
        const formatDateForDisplay = (dateTime?: Date | string) => {
            if (!dateTime) {
                return '';
            }
            const date = typeof dateTime === 'string' ? new Date(dateTime) : dateTime;
            return moment(date).format('YYYY-MM-DDTHH:mm');
        };

The console in the frontend shows it to me as expected, but I have read that it already performs formatting.

F12 console: setting from: 2023-12-11 08:49:00 +01:00 to 2023-12-17 09:49:00 +01:00

Backend:

   [HttpPost]
    [Route("")]
    public async Task<ActionResult<Setting>> CreateSetting([FromBody] Setting setting)
    {
        try
        {
            .....
        }
        catch (Exception ex)
        {
....
        }
    }

    public class Setting : xxx
{
    public DateTimeOffset? ValidFrom { get; set; }
    public DateTimeOffset? ValidTo { get; set; }
    public DateTimeOffset? LastUpdate { get; set; }}

The LastUpdate Date appears one hour too early in the backend due to the absence of the time zone. In the backend, I set the LastUpdate Date using DateTimeOffset.Now. This writes the value, including the time zone, correctly into the database.

Thanks and bye