You used the word "sent" earlier and the phrase "on my device" now. But it seems the app isn't transferring the message to you, only presenting it -- like a web

You used the word "sent" earlier and the phrase "on my device" now. But it seems the app isn't transferring the message to you, only presenting it -- like a website. (Does the message exist outside the app?) Not being pedantic for the sake of it, just pointing out the language you are using is from a position of ownership -- you receiving and owning a message sent to you, and it is then being deleted -- while the app seems to be retaining all rights with the sender, who merely uses the app to present a message to you, and can revoke viewing privileges at any time.