All applications receive data from other applications

I’m posting on behalf of a customer.
They have created multiple applications (Server-to-Server OAuth). One for each of their environments (TEST, QA PROD, ETC…).
Every application has its own unique webhook address which sends data to it’s environment. The problem we encountered is that when creating a meeting in one application all application hooks receive data event though the meeting was made in one application. This behavior seems faulty.
Is this the design? How can they make sure each application received only its own meetings data?