Only 50% of the relative loss of transit agencies is subsidised by the federal government, the other 50% gets subsidised by the respective state. And since the compensation is calculated in relation to the prices of monthly subscription tickets on routes in the respective transit area, transit agencies are left with even less.
Additionally, a lawsuit determined that the train network price cap for public transport is illegal, further increasing costs for the states.
This already has caused service reductions in multiple states, e.g. just now in Berlin additional overground Metro services during commuter peaks got halfed. With the results of the lawsuit and now interest from the federal goverment to put more funding into public transport, a lot more services will get axed in the next 3 years.
But the biggest problem for the german trains remains the management of DB (Deutsche Bahn). Who are in charge of the network.
Who paid themself heavy bonuses all the time, while failing on all the metrics that mattered (they succeeded on making a new useless info page go live, that was the official justification for the bonus).
And they could do this, because the job of the ministry of transport was to make it easy for the car industry. And the german train is in theory privatized, in reality not so much.
The current ministry might be better though, so maybe something is happening. But I believe it, when I see it.