This worked for me (.NET Framework 4.8.1) VS 2022 C# The JSON or any serializer object need to be generated with not to include typeinformation settings. Below is an example:

var settings = new DataContractJsonSerializerSettings();
settings.EmitTypeInformation = EmitTypeInformation.Never;

var serializer = new DataContractJsonSerializer(yourType, settings);

or

var serializer = new DataContractJsonSerializer(yourType, new DataContractJsonSerializerSettings() {EmitTypeInformation=EmitTypeInformation.Never});

Thanks to: Daniel https://stackoverflow.com/users/572644/daniel-hilgarth in

How do I tell DataContractJsonSerializer to not include the "__type" property