Sure, it is a huge achievement. He's the youngest rider to podium a GT in, I don't know, over a century I think? But 3rd in Madrid and 4th after two weeks aren't the same thing.
Do you mean Ayuso is different, or do you mean the combined performances of Ayuso, Pogačar, Evenepoel and other wonder kids?
I should probably clarify: when I say things like this, I don't mean they're clean. Mostly I look at performances like: is this "normal" for the peloton in its current state? Or is this over the top and suggests either heavier-than-normal doping, some kind of medical advantage, or (potentially)UCI corruption? When I see something as "normal for the peloton in its current state", that means I tend to think that how cleannish or heavily doped it is depends on how cleannish or heavily doped the peloton at large is (my impression for a decade now has been that the peloton has steadily become more and more heavily doped, or rather more efficiently doped, but we don't have a lot of data). Now, since I very much doubt that it's currently possible to perform at this level while riding clean, I would say Ayuso is probably a doper. But that's hardly noteworthy in itself.
My current theory for why so many youngsters are performing at the highest level is quite simple. Some time ago it would seem it was customary for very young riders and neo pros in serious teams to stay off the dope. This was so their potential could be assessed accurately, and also to ease them in. This was the reason why the top teams would often only trust their feeder teams. Perhaps that's not the current practice anymore, maybe teams feel they can assess a rider's potential accurately enough even if they get on the program immediately, or maybe the need for immediate results has proved more important than these concerns in the long run.