After use overtrue/wechat 4.x, the refund request not work well

After https://www.drupal.org/project/commerce_wechat_pay/issues/2997365, we now found two errors about refund request.

1. If we pay 0.01, refund 0.01, it works well.
   But if we pay 2.01, can not refund it.
   The error message will likes:

   err_code：REFUND_FEE_MISMATCH err_code_des：订单金额或退款金额与之前请求不一致，请核实后再试

2. If we pay 0.02，first time we refund 0.01，it works well.
   Then refund 0.01, we can not see the refunded record on wechat APP.