When i set RetainArgumentTypes to true in FunctionChoiceBehavior it start sending parameters in correct format.

var executionSettings = new OpenAIPromptExecutionSettings
{
    Temperature = 0,
    //FunctionChoiceBehavior = FunctionChoiceBehavior.Auto()
    FunctionChoiceBehavior = FunctionChoiceBehavior.Auto(options: new() { RetainArgumentTypes = true })
};