[MertsA]

iMessage is not on the same playing field as Whatsapp and Signal. Apple has full control over key distribution and virtually no one verifies Apple isn't acting as a MitM. Whatsapp and e2e encrypted messenger force you to handle securely linking multiple devices to your account and gives you the option to verify that Meta isn't providing bogus public keys to break the e2e encryption.

https://engineering.fb.com/2023/04/13/security/whatsapp-key-...

For iMessage, Apple can just add a fake iDevice to your account and now iMessage will happily encrypt everything to that new key as well and there's zero practical visibility to the user. If it was a targeted attack and not blanket surveillance then there's no way the target is going to notice. You can open up the keychain app and check for yourself but unless you regularly do this and compare the keys between all your Apple products you can't be sure. I don't even know how to do that on iPhone.