While there have been some tweaks around the edges in terms of congestion control and the like, the TCP wire format has not changed in over 25 years and it has

While there have been some tweaks around the edges in terms of congestion control and the like, the TCP wire format has not changed in over 25 years and it has very little to do with Windows. It has to do with the all the middle boxes and routers in the ossified backbone of the internet that choke if they see anything over IP that is not exactly what they expect.