Alma sends a cancellation message of a Resource Sharing borrowing request to a partner when a requester cancels this request in Primo. (Notifying a campus library to which a requester is assigned about a request cancellation is fine, but external partners should not be informed.)

There should be an option in Alma to prevent patrons' cancellation requests being sent to external partners, as this is currently not possible:

https://knowledge.exlibrisgroup.com/Alma/Knowledge_Articles/Resource_sharing_requests/Resource_Sharing_Request%3A_when_cancelled_by_patron_via_Primo%2C_a_cancellation_letter_is_sent_to_the_partner.