See below a link to an article in La Gazetta dello Sport. It's in Italian and I can't yet find a full English translation. It is a 'Decreto legislativo' so this is a national piece of legislation.
This makes it compulsory for those using 'alpine ski pistes' to have insurance which covers for third party risk. It's similar to it being compulsory to have this insurance for cars here in the UK.
The only exclusion that I can see is for cross country ski-ing (sci fondo in Italian). Ski tourers should be aware of this as well, if you go onto piste areas. There is provision for enforcement with fines, 100 to 150 Euros and they will remove your ski pass. In the next couple of years, I am sure the piste Police (which in Italy are 'real police) will be enforcing this.
If you do take your own insurance, it will almost certainly require an Italian translation to prove cover.
It comes into force 1st January 2022
I'll forward this to the BMC although their insurers are I am sure aware.
Other readers / speakers of Italian, please have a look at it and just check my understanding.
https://www.neveitalia.it/assicurazioni-sci/news/assicurazione-obbligatoria...