Users are getting "chat notifications" through ServiceNow for change requests in the connect chat window.
The following Business rule is causing the conversation records to be created.
Refresh Impacted Services - https://<instance-name>.service-now.com/nav_to.do?uri=sys_script.do?sys_id=08cf6ffe23203300a5eedc1756bf657f
As you can see this calls a script includes ChangeUtils which is an extension of another script include "ChangeUtilsSNC". The function "refreshImpactedServices" calls the function getImpactedServicesFromAffectedCIs which in turn calls "_notifyUser". The _notifyUser function creates a new chat conversation with the change request number as the display value(check line number 460).
ChangeUtilsSNC - https://<instance-name>.service-now.com/nav_to.do?uri=sys_script_include.do?sys_id=2ddf83eb9fa331002920bde8132e7044
This is sending out the message to the message with the change request number as you see.
This business rule is for updating the task_cmdb_ci_service (Impacted Services) table with the configuration item you have selected for the change request. So we would as you not to turn off the OOB business rule. If you do not want the OOB behavior, you can customize the ChangeUtilsSNC script include through the extension "ChangeUtils".