I recently took the first direct train from Prague to Copenhagen which was expected to take 13 hours from PRG to CPH (normally it should be 11 but there is a construction on the high speed line between Berlin and Hamburg so we had to take a detour through Uelzen).
The train left the Czech Republic with 0 minutes delay. Long story short, we crossed the German-Danish border more than FIVE hours later than the original plan. And it wasn't even in the same physical train, the original one got cancelled from Hamburg because of the huge delay we already had.
As for the reason of the delay, at first it was just German "normal" state of things, we left Bad Schandau (the first German station) on time, got to Dresden with 5 minutes (still "on time" according to DB), then without any visible reason got 20 minutes on approach to Berlin where there were so many people on the platform that it took some other twenty minutes for the passengers to get on and off.
When we arrived to Luneburg, the train stopped and after an hour or so the crew said that there is a problem on the line to Hamburg so we'd have to take another detour (from a detour!) and go through Hannover which added several hours to our delay. On approach to Hamburg we already knew that we'd have to transfer to a Danish train there, which thankfully went pretty fast and we left for Schleswig, where our train stopped again, this time because of a "fire in the vicinity of the tracks". After another two or three hours that it took the firefighters to realize that nothing was actually burning, we finally left Germany and the rest of the trip went just fine and we did not gather any additional delay in Denmark, arriving to Copenhagen in the middle of the night (instead of the original 7:30pm).
TL;DR: Sänk ju for trävelin wiß Deutsche Bahn!
Czech media even wrote[1] about how the train failed to get to its destination.
[1]: https://zdopravy.cz/prvni-primy-vlak-z-prahy-do-kodane-skonc...