How to prevent GraphQLClient.SendQueryAsync change my Key's case

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Hello!
How can I prevent GraphQLClient.SendQueryAsync(myquery) change my Key's case?
Before sending I can see the part of my variable is
ID = "ZX", and API is expecting "ID", but on Fiddler I see this variable is {"id" : "ZX", ...}, and response error says: got invalid value {id: "ZX", ...} at xxx; Field "id" is not defined.... Did you mean "ID" ?

Any suggestions?
Thanks!