gistfile1.txt

using Q75832457;
using System.Text.Json;

JsonSerializerOptions JsonSerializerOptions = new()
{
    PropertyNameCaseInsensitive = true
};

string json = @"
[
  {
    ""rawMessage"": ""adsfasf a\u00F6dsij\u00F6oi \u00F6jadf"",
    ""dateTime"": ""2023-03-24T10:04:05.6560707+01:00"",
    ""senderCompId"": ""BB"",
    ""targetCompId"": ""PRIOR"",
    ""targetSubId"": ""EMSX"",
    ""sent"": false
  }
]";
List<Message> messages = JsonSerializer.Deserialize<List<Message>>(json, JsonSerializerOptions);
Console.WriteLine(messages.Count); // Prints 1