Yeah, except for the DERP protocol, my impression is that it's what they do in Tailscale but don't claim that what they have done is new. They even referenced STUN's RFCs, so I don't think that they are misrepresenting anything as new but simply describing in detail how their product works.

Yeah and from what I remember, DERP has some design choices that differentiate from STUN/TURN and that’s exactly how it’s presented.