I find food in Bordrestaurants on german trains often mediocre - everything is pre-cooked and then microwaved, and in approximately half of my journeys service is somewhat reduced (ranging from being out of certain items to being fully closed). But hey, prices are not thaaat bad (especially with the 30% discount you get as “BahnBonus Platin” member), it’s edible and they offer more and more veggie options.

I looked into it a bit more and seems like we are both somewhat right: https://www.tz.de/muenchen/stadt/guenstige-jetzt-jagt-ihn-das-finanzamt-das-ist-ein-unding-preise-muenchen-vermieter-65-verlangt-zu-zr-91597287.html

I’m not sure this is exactly the argument, I understood it as: “You rent out so cheap you don’t want to make a profit, and if you don’t want to make a profit you can’t make deductions in relation to your properties.” Which I don’t find great either.