How to find an event handler?

Question

1C-Bitrix

Good afternoon.

A new status was created for orders, called it "Ready for shipment", the status code was assigned "RD".
If you change the status of an order but this new one, for example, in the admin panel (or via api), then in addition to the fact that the status of the order is set to the specified one - "Ready for shipment", the order also becomes cancelled.
In the order history of the order change, it looks like:
04/22/2021 17:28:07 - Order reservation
canceled 04/22/2021 17:28:07 - Order
canceled 04/22/2021 17:28:07 - Status changed to: "Ready for shipment"

When changing the order status to any other does not happen.

How to find the culprit, who does it? what cancels the order?