Even with e2e security there is 2 e’s that can get compromised, their use of a altered version of the app on one end is enough to cancel out the whole encryption part it, also on the other end.

But in this case it’s like they have a lock for their garage door that is different from the lock on their car so they can’t steal the car when somebody steals the key to the garage door, but then think they can leave the keys in the lock because there is a lock (encryption) on the doors.