If you are messaging someone who is not using the latest version of Apple's software, you may not be able to use the ability to edit and unsend messages. According to 9to5Mac, a messy workaround is included in the latest version of the software that will allow new iMessages to be sent on the phone. It could make anyone in a group chat annoyed.
If someone tries to edit an iMessage sent to a device with an older version of the software, the edit will be preceded by the words "Edited to." When trying to edit a message sent to a non-iOS 16 device, the previous developerbetas wouldn't send anything. The new approach looks complicated for the recipient. After an edited version is sent, Apple's software is not able to remove the original message.
Edited to “It’s a messy workaround”
The issue is unlikely to persist for a long time since Apple is very quick at getting new versions of its software rolled out. It could prove to be annoying for people who use a pre-2017 Apple device. Being able to view an unvarnished message is an advantage.
When sent between the two operating systems, it is a similar mess. There is a solution to the problem, with Apple planning a similar update with the new version of its operating system. It is hoped that a solution will eventually emerge for iMessages.