Whenever a new Webex Meeting is created in Outlook, the participants who decline the meeting and select "Do Not Send a Response" to the meeting creator will continue to receive the meeting notifications in the Webex app until declining it and send a response to the creator.
This is because the Webex app only filters out the declined attendees and sends a response to the organizer. The request is to avoid receiving the join meeting notifications from the Webex app without the need to select "send a response" and just by declining it.
Without this feature implemented, it inundates the meeting creator with excessive non-needed declined emails. Also, it is a privacy issue for the attendee, who may not want the meeting creator to know their decision to decline to attend the meeting.
Please reference Cisco Internal Feature Enhancement Request (FER) with ID: "COLLAB-I-18835"