I don’t know for Deutsche Bahn, but in several countries there’s a night break (like Belgium), which forms the barrier for the use of your ticket. Which means you can take a train after midnight, with a ticket from the day before. Usually there are not many trains, and the trains that are going usually started their trip before midnight.

You’lld better ask at a DB information point, what the specifities of those rules are.

Have you considered leaving Venice a bit earlier?

Alternatively book your pass to last station in Austria and pay for the section to Munich. That leaves your last day for Munich to home.

Mann kann dies nur entweichen-und das soll an sich eigentlicjh ganz logisch sein, mit frueher ab VNZ abhfahren -und dann wenigsten 2 St frueher in M an zu kommen um dann noch-bahn.de nachsehen wie es geht,mit letzter ICE des tages bis S zu fahren-je nach Heimort muss mann dann nur noch VVS zuzahlen.

No, can’t be avoided beside taking another (earlier or later) departure. Maybe best to go until Salzburg/Kufstein and then use Bayern Ticket Nacht to München. From there use your inbound then for the 0.01 train as another user suggested.
 

Thanks all for the helpful comments. I have now settled on taking the earlier train from Venice, so I catch an ICE before midnight in Munich, so I only need to pay for a ticket from my local Verkehrsverbund after that.

It’s really unfortunate that the rules around travelling to/from the home country are so strict. I found that to be a real downside to interrail travel, since I already had to pay full price when leaving the country, because at one point in my journey I wanted to travel by night train across my home country (without exiting the train in Germany), so I had to save my outbound journey for that.

I could imagine one or more of these changes would improve the experience around that a lot:

• instead of two calendar days in your home country you are allowed two 24h periods in your home country
• move the dividing line between travel days past midnight to when most trains stopped running (e.g. 3 or 4 AM)
• allow through-journeys (at least when not changing trains inside the country)
• add a third or fourth inbound/outbound travel day as a buffer

Unfortunately there are unscrupulous people out there who would abuse the system, plus technical problems with the “any 24 hour day” only applying to the In/out days. 

The change in the start time of a travel day would not help many people  and possibly inconvenience as many as it helps. (It isn’t going to happen)

There has been debate about passing through your home country without leaving the train, but that is simply fraught on trains that make a scheduled stop in your country. I believe trains that have no scheduled stop in your home country wouldn’t trigger the I/O day, but they are few and far between.  Imagine you were boarding a train from Munich to Strasbourg. What would stop you getting off at Stuttgart? There is nothing stopping anybody putting a start point in country A, boarding in country B (their home country) and leaving in country C. An theoretical example would be a Belgian logging Amsterdam to London but not boarding until it reached Brussels.

Adding extra days is possible for those who can show they cannot realistically cross their country to leave in a normal day. I believe this would include the North of Sweden to leave to the south. However this is strictly discretionary and you need to apply to customer service.