Refit exception system.Text.Json.JsonReaderException: 'M' is an invalid start of a value

Question

I am using Refit version 6.0.94. I have a .net 5.0 Api and a Blazor Server app .Net 5.0. The Api and Web app are both deployed in Linux containers. When running locally in visual studio (windows 10) I do not get the error.

The Get and Delete verbs are working fine, but the Patch and Post are failing with exception

System.Text.Json.JsonException: 'M' is an invalid start of a value. Path: $ | LineNumber: 0 | BytePositionInLine: 0. ---> System.Text.Json.JsonReaderException: 'M' is an invalid start of a value. LineNumber: 0 | BytePositionInLine: 0. at System.Text.Json.ThrowHelper.ThrowJsonReaderException(Utf8JsonReader& json, ExceptionResource resource, Byte nextByte, ReadOnlySpan`1 bytes) in //src/libraries/System.Text.Json/src/System/Text/Json/ThrowHelper.cs:line 280 at System.Text.Json.Utf8JsonReader.ConsumeValue(Byte marker) in //src/libraries/System.Text.Json/src/System/Text/Json/Reader/Utf8JsonReader.cs:line 1034

The Api Code is Here

[HttpPatch]
public async Task<IActionResult> PatchAsync([FromBody] Customer customer)
{
   return Ok(await _service.PatchAsync(customer));
}

The Poco code as follows

namespace CustomerCare
{
    public class Customer
    {
        [JsonPropertyName("Name")]
        public string Name { get; set; }
                    
        [JsonPropertyName("Surname")]
        public string Surname { get; set; }
                
        [JsonPropertyName("Id")]
        public int Id { get; set; }
            
        [JsonPropertyName("SignupDate")]
        public DateTime? SignupDate { get; set; }
    }
}

Refit setup and definition

services.AddRefitClient<ICustomerService>().ConfigureHttpClient(c => c.BaseAddress = new Uri("http://myservername/api/v1"))
                    
public interface ICustomerService
{
    [Delete("/CustomerCare/")]
    Task<bool> DeleteCustomer(int id);

    [Patch("/CustomerCare/")]
    Task<bool> PatchCustomerAsync([Body] Customer customer);

    [Get("/CustomerCare/{id}")]
    Task<Customer> GetCustomerByIdAsync(int id);

    [Post("/CustomerCare/")]
    Task PostAsync([Body] Customer customer);
}

The calling code is as follows

    try
    {
        return await _customerService.PatchCustomerAsync(customer);
    }
    catch (ApiException ex)
    {
        var errors = await ex.GetContentAsAsync<Dictionary<string, string>>();
        var message = string.Join("; ", errors.Values);
        throw new Exception(message);
    }