(Take it with a bit of neighbourly humour.)
https://www.thelocal.de/20230410/more-than-a-third-of-german...
[1] https://www.irishrail.ie/en-ie/about-us/train-punctuality-re...
You may have had a good experience here in Germany as a tourist, but it's simply not reality. Trains are not reliably on time here these days, and it's a huge problem.
I do not doubt the DART is unreliable in Dublin, the buses are just as bad (I moved to Germany from Dublin a little over a year ago). I know it's a bit apples to oranges comparison between Germany and Ireland, but I can assure you, it is bad here in Germany currently!
I've traveled in a lot of countries and used train in a lot of them, none of them have been quite as bad as DB when it comes to reliability.
And the recent articles that claim only around 60% of trains arrive on time bears that.