The fake app, when downloaded, installs a "variant of the Coper trojan" malware on the target's device
Coper / Octo - A Conductor for Mobile Mayhem… With Eight Limbs?
https://www.team-cymru.com/post/coper-octo-a-conductor-for-mobile-mayhem-with-eight-limbs
Unlike email, there is a cost associated with sending each piece of physical mail, so this attack method must be delivering some level of success to the scammers behind it.
Microsoft just the other week reported more than 15,000 messages with malicious QR codes targeting the education sector had been sent every day over the past year
https://www.theregister.com/2024/10/13/schools_nationstate_attacks_ransomware/