Most recent contact note exposed in event confirmation emails

• Create an event where the on-line registration profile contain a Contacts:Note field.
• Contact leaves that field blank during form submission.
• Result: Contact receives a confirmation email showing the most recent note on that contact.

Not sure if this behavior is intentional, but I consider it problematic.

• a) Showing a contact a note he might have submitted years ago is rather confusing.
• b) Backend users may have an expectation of confidentiality when they add notes to a contact record, believing that info will never be exposed to the contact.

Confirmed on CiviCRM 5.13.4, 5.15.1.