There is a discussion right now in the Magento community about whether canceling a PayPal checkout modal should be communicated to the user as a success or failure. This same question could also apply to other payment methods that take the user outside the immediate context of the checkout to approve payment, such as Google or Apple Pay.
The arguments for each are:
Sucesss: "You requested me to interrupt the payment operation, so I've done that for you"
Error: "The order was not was not placed successfully, which is a failure"
My argument there is that the type of message needs to be determined within the broader context of the checkout intent, inclining towards it being an error. However, I and most others in the discussion are devs/engineers primarily, so I'm hoping for some input from UX designers.
(For context, Magento uses different presentational styles for success and error messages, with the third possibility of a neutral "notice" as well.)