Your case should be covered by EU passenger rights (Regulation (EC) 1371/2007).
According to the regulation you should be able to get a refund of 50% of the original ticket price. Additionally they should refund the ticket for the new train (but you should have asked Deutsche Bahn employees in Munich on that day whether they would unlock your original ticket for the morning connection).
According to this Trenitalia leaflet you can submit a claim on their website.
I have no direct experience with them and therefore don’t know how problematic getting a refund is in practice.
Credit:stackoverflow.com‘
4 Mar, 2024
5 Mar, 2024
4 Mar, 2024