They have ephemeral messaging where one can set a timer to delete a message when it is read or from the time it was sent. But that isn’t always so easy to gauge with life. Often times a chat log is needed when people don’t check it often or right away. So the group must set a long timer like 24h ect ect. It’s customizable. But if a group members device gets lost or stolen ect. It is of no use. Signal by default stores all call logs in the app. Even if the ephemeral timer is short. Call logs require manual deletion and the group is still formed showing who was in that group but the chat will be empty. Edit was wording.