Yes, average speeds have gone up but that's not purely down to physiology. If it was possible to look at the distribution of speeds during the stages that would likely tell the true story - more time spent at higher speeds because the racing starts earlier & there are fewer soft breakaways.
Tadej Pogačar obliterated record after record on his way to a fifth career Tour de France title, in the fastest edition in the race’s history. But what do the peloton’s ever-increasing speeds mean for the sport, its safety, and its credibility?