Strange thing to bear in mind, as I understand it airbags are pyrotechnical devices, ie fireworks, they do not have stored gas at pressure in a reservoir so there can not be a partial escape of gas that might cause this situation. Maybe Alfa redesigned the dash to improve the deployment. By the way what Jahrebauzeit haben sie? that was for the OP and you if you are where you say you are?
It's a 2012 model. The left picture is from an Italian forum, the right one is mine. I only saw the outline of the airbag before, I think it's getting really slowly worse.
I've found that other makes and models (Fiat Bravo, 500, Mazda RX-8, Mercedes, etc.) can also have this problem, mainly in countries with hot climate.
Here's a comment from Fiatt 500 owner from Israel:
Eventually, I started looking at Fiat's for sale online, looked at pictures, and on alot of the cars, the dashboard was inflated.
"I also started looking into Fiat's while walking the street, and I could barely find 1 Fiat that *DIDN'T* have a cracked or inflated dashboard.
I started looking at other cars made by Fiat, such as Alfa Romeo.
By now I wasn't surprised to see that in the Giulietta the dashboard was inflated as well.
Its important to mention that all the cars that I saw that had inflated or cracked dashboards were 2 years old and older, so my guess is that this issue is age related."
Of course, it's only cosmetic (the thin plastic above the airbag deforms easily), but still annoying.
The only solution is to replace the dashboard, or remove it and wrap in leather.