Well these apps don’t even let you verify the keys even if you wanted to, so you can’t even tell if it’s being man-in-the-middle’d.

Some people said they are finally adding key transparency features to let you do that, but it should have been there since the start. Something a lot of people already use called SSH literally has had that since forever. It’s like basic 101 cryptography if you design an encrypted protocol that isn’t using a trusted third party for key verification (like certificate authorities in TLS/SSL).

If you implement ANY encrypted protocol, key verification is extremely important. If you aren’t verifying keys are possessed only by your recipient, you cannot verify who can read your message.