【请求数据】：{"transaction_id":"4200001178202108253142057633","amount":16800,"out_order_no":"BCR202108311209013499989","description":"用户退款平台补差回退","sub_mchid":"1609826329","refund_id":"50300809312021083112022347914"}

【响应数据】：{"amount":16800,"description":"用户退款平台补差回退","from":[],"out_order_no":"BCR202108311209013499989","refund_id":"50300809312021083112022347914","result":"FAIL","sub_mchid":"1609826329","subsidy_refund_id":"41000109322021083100154208140","success_time":"1970-01-01T08:00:00+08:00","transaction_id":"4200001178202108253142057633"}

请帮忙查看这个订单补差回退失败的原因

另：

1、请问一下补差的钱现在是补到商户的不可用余额了吗，最开始开发的时候是补差到可用余额的，逻辑变了吗 ？

2、补差回退的钱是从哪个账户退出的，有时候是不可用余额，有时候又是可用余额，这个具体标准或者节点是什么