What are those random emojis in voice calls for, then? I assume (warning: assumption) the voice calls are actually encrypted, even if it's with keys received fr

What are those random emojis in voice calls for, then? I assume (warning: assumption) the voice calls are actually encrypted, even if it's with keys received from the server and opportunistic unless you verify the emojis for a particular call. (Video I don't know, and group chats and most 1:1 chats are definitely plaintext yeah.)