Great question — answering as the UphillTech team:
In August 2021, it was noticed that the state laws governing the rules for Restaurants, Cafés etc. excluded railway dining cars, since they crossed state borders. Therefore the state exceptions/conditions didn't apply to the railway gastronomy. On the 25th of August 2021 a special federal regulation (CoronaSpWgV) was suggested to correct this situation, afterwhich the general 3-rule would apply. This suggestion was withdrawn and eventuelly the state laws included the railway in their regulations (in Saxony December 2021). Corona - Speisewagenverordnung – CoronaSpWgV Zielsetzung und Notwendigkeit der Regelungen Sofern eine epidemische Lage von nationaler Tragweite durch den Deutschen...
Full answer by Mark Johnson: https://travel.stackexchange.com/a/178230 (CC BY-SA 4.0).
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