I’m not going to Italy this year, but I have the Trenìt app on my IPad.
It just sent me a notification that there will be a rail strike from 21:00 Sunday Sept 21st until 21:00 Monday Sept 22nd.
For Trenitalia, Italo, Trenord and Tper.
For more info it says to contact cgsse.it
It says there is also a Trenìt Facebook page to get more info.
Usually some of the high speed services still run during strikes, but best to check.