In Mail v16.0 (under mac OS 15.5) messages sometimes disappear after using unsend function.
About 10% of my emails disappear after I use the unsend function. Usually I get back the email to edit, but sometimes it will be deleted immediately, and can not find in any Mail folder. This problem occured in previous macOS versions too. It is a MacBook Pro M1 Max.
MacBook Pro 14″, macOS 15.5