IAP - Rejected, Cancelled, Pending Purchases, why?

Hello,

I have several applications with in-app purchases of Google Play products. For quite some time now we have had problems with purchases in several of these applications. Some are done correctly, but many of us have these statuses in the order manager:

Payment rejected
Canceled
Pending payment

and the number of orders with these statuses is increasing. We have been updating the IAP version, we have version 4.12.0.

We are not sure why they are rejected, cancelled or the payments are pending.

What is a good practice or how can we obtain more details about these statuses? We need to know if it is an IAP problem or if users are cheating or cancelling the purchase.

What do you recommend we do?

Thanks!