So, crypto part or mtproto in general? I’m not a fanboy who is going to defend tg crypto, and personally I wonder why they didn’t use the same security stack e.g. my browser uses for gmail access. But apart from that it feels to me like a regular rpc protocol, clumsy sometimes, but nothing particularly weird. Working also with many stock exchanges protocols, I can tell these are sometimes weird af, despite being mostly over-https. E.g. bitfinex and iirc bitmex are funny ones, not to mention FIX/FAST or large exchanges native protocols.