Deutsche Bahn trains facing delays are now being stopped at the Swiss border if they are too unpunctual, a measure introduced in July 2022 and becoming more common. In the first quarter of 2024, over 10% of German trains were halted at the border due to late arrivals, a significant increase compared to the previous year. This regulation, initially temporary, has now become permanent, with Swiss Railways allowing a buffer of 10-15 minutes for trains before rerouting. The significant difference in punctuality rates between Switzerland and Germany is cited as the reason behind this stricter enforcement.
https://www.bluewin.ch/en/news/switzerland/more-and-more-german-trains-are-not-allowed-to-enter-switzerland-2304207.html