When manually creating a new opportunity with a contact that already exists, the system displays an error message—but still proceeds to create the opportunity. As a result, a new contact is created without a phone number, which causes automations to fail in sending messages.

To prevent this issue, I suggest two possible solutions:

Enable searching for an existing contact by phone number directly from the "Create New Opportunity" form.

Postpone contact creation until the "Create Opportunity" button is clicked. If a duplicate phone number is detected at that point, display a warning and avoid creating the new contact.

Ideally, both solutions should be implemented to ensure reliability and a smooth workflow.